Updated constraints due security reasons (triggered on 2026-10-12T20:59:05+00:00 by 3d08b2ef7a182c6dd6553d92c7fdd21fdc75f661)

[github-actions]

Fixed dependency issues for Python 3.10

Name	Version	ID	Fix Versions	Description
urllib3	2.7.0	PYSEC-2026-4177	2.8.0	## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees \n or EOF. A malicious HTTP server can return Transfer-Encoding: chunked and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected when streaming a chunked response from untrusted sources. Specifically, this affects the read_chunked() and stream() methods of the HTTPResponse object. This also affects requests streaming API, which uses urllib3 under the hood. ## Remediation Upgrade to urllib3 version 2.8.0 or later, where chunk-size fields larger than 65536 will be rejected. If upgrading is not immediately possible, consider reading the response at once using the read() method.
urllib3	2.7.0	PYSEC-2026-4176	2.8.0	### Impact urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading content in chunks instead of loading the entire response body into memory at once. urllib3 can decompress response bodies according to the HTTP Content-Encoding header. When streaming a compressed, chunked response, urllib3 first consumes data already buffered by the decoder before reading the next HTTP chunk. However, urllib3 versions from 2.6.2 through 2.7.0 could enter an infinite loop when a chunked response contained bytes after the end of the Deflate stream. If the decompressed body exceeded the requested streaming chunk size, Python's zlib implementation could retain the trailing bytes as unconsumed input after reaching the end of the compressed stream. urllib3 would repeatedly attempt to decode those same bytes without making progress or reading more data from the network. A malicious server could exploit this behavior to cause excessive CPU usage and prevent the affected request from completing on the client. Network read timeouts would not interrupt the loop because no further socket operation was required. ### Affected usages Applications and libraries using urllib3 versions 2.6.2 through 2.7.0 may be affected when all of the following conditions are met: 1. Compressed responses from an untrusted source are streamed using HTTPResponse.stream(amt=N) or HTTPResponse.read_chunked(amt=N) with a positive, finite chunk size. 2. Content decoding is enabled. 3. The response uses both Transfer-Encoding: chunked and Content-Encoding: deflate. 4. The decoded body exceeds the requested chunk size and the encoded body contains bytes after the end of the Deflate stream. HTTPResponse.stream() uses a finite chunk size by default and is therefore affected when the other conditions are met. ### Remediation Upgrade to urllib3 2.8.0, in which the Deflate decoder stops accepting input after reaching the end of the compressed stream and no longer reports trailing bytes as data that can produce more decoded output. If upgrading is not immediately possible, disable automatic content decoding for responses from untrusted sources by setting decode_content=False, or reject streamed responses using the Deflate content encoding. Applications that disable automatic decoding must handle the compressed response safely at another layer.
urllib3	2.7.0	PYSEC-2026-4175	2.8.0	## Impact urllib3 supports configuring TLS independently for an HTTPS proxy and the target server. proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server. In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could: 1. Ignore proxy_ssl_context and use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. 2. Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy. 3. Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy. In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context. An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust or identity policy is incorrectly applied to the proxy connection. When HTTPS forwarding is enabled, an impersonated proxy can observe or modify forwarded requests and responses, potentially exposing credentials, authentication tokens, request bodies, response data, and other sensitive information. A TLS client certificate intended for the target server may also be presented to the proxy or to an attacker impersonating it. This can disclose the client's identity and provide proof of possession of the corresponding private key. The private key itself is not transmitted during the TLS handshake. In CONNECT tunneling mode, impersonating the HTTPS proxy does not by itself defeat the separate end-to-end TLS connection between the client and the target server. ## Affected Usages Code using urllib3 versions 1.26.0 through 2.7.0 may be affected in any of the following cases. ### 1. The target SSL context is used for an HTTPS forwarding proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and proxy_ssl_context is configured for the proxy. urllib3 may ignore proxy_ssl_context and use the target server's ssl_context for the proxy TLS handshake. The proxy may therefore be verified using the target server's trust and certificate policy instead of the policy explicitly configured for the proxy. ### 2. The target verification policy overrides the proxy policy An HTTPS proxy is configured with proxy_ssl_context, while the target server uses a different certificate-verification policy. urllib3 may apply the target server's cert_reqs value to the proxy SSL context. For example, setting cert_reqs="CERT_NONE" for the target server may also disable certificate verification for the HTTPS proxy, even when proxy_ssl_context was configured to require verification. This issue can affect the TLS connection to an HTTPS proxy in both forwarding and CONNECT tunneling configurations. ### 3. A mutated proxy SSL context is reused The same SSL context is reused as proxy_ssl_context across multiple connections, and certificate verification is disabled for one target server. urllib3 may modify the proxy SSL context's verify_mode in place. Later connections that reuse the same context may therefore connect to the HTTPS proxy without certificate verification. ### 4. Target-specific TLS identity or credentials are applied to the proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials are configured. urllib3 may apply these target-specific settings to the proxy TLS handshake. This may cause urllib3 to: - send SNI intended for the target server to the proxy; - verify the proxy using a hostname or certificate fingerprint intended for the target server; or - present a TLS client certificate intended for the target server to the proxy. Code connecting through a plain HTTP proxy does not establish a TLS connection to the proxy and is not affected by this issue. ## Remediation Upgrade to urllib3 2.8.0 or later. urllib3 2.8.0 independently applies the explicitly configured proxy_ssl_context and proxy-specific certificate assertions to the HTTPS proxy connection. Target-specific SNI, certificate assertions, and TLS client certificate parameters are no longer applied to the HTTPS proxy handshake. For backward compatibility, when an HTTPS proxy is used with use_forwarding_for_https=True and proxy_ssl_context is not provided, urllib3 2.8.0 continues to use ssl_context for the TLS connection to the proxy. This configuration emits a FutureWarning. In urllib3 3.0, passing ssl_context with use_forwarding_for_https=True for an HTTPS proxy will raise an error. Applications should use proxy_ssl_context to configure TLS for an HTTPS forwarding proxy. The fixes were implemented in commits b6447295fff7b38fdffc67e0df9712d60cef3cc3 and 07408cec79d1856d81bb42c74a904a24fdb9e465.

Fixed dependency issues for Python 3.11

Name	Version	ID	Fix Versions	Description
urllib3	2.7.0	PYSEC-2026-4177	2.8.0	## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees \n or EOF. A malicious HTTP server can return Transfer-Encoding: chunked and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected when streaming a chunked response from untrusted sources. Specifically, this affects the read_chunked() and stream() methods of the HTTPResponse object. This also affects requests streaming API, which uses urllib3 under the hood. ## Remediation Upgrade to urllib3 version 2.8.0 or later, where chunk-size fields larger than 65536 will be rejected. If upgrading is not immediately possible, consider reading the response at once using the read() method.
urllib3	2.7.0	PYSEC-2026-4176	2.8.0	### Impact urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading content in chunks instead of loading the entire response body into memory at once. urllib3 can decompress response bodies according to the HTTP Content-Encoding header. When streaming a compressed, chunked response, urllib3 first consumes data already buffered by the decoder before reading the next HTTP chunk. However, urllib3 versions from 2.6.2 through 2.7.0 could enter an infinite loop when a chunked response contained bytes after the end of the Deflate stream. If the decompressed body exceeded the requested streaming chunk size, Python's zlib implementation could retain the trailing bytes as unconsumed input after reaching the end of the compressed stream. urllib3 would repeatedly attempt to decode those same bytes without making progress or reading more data from the network. A malicious server could exploit this behavior to cause excessive CPU usage and prevent the affected request from completing on the client. Network read timeouts would not interrupt the loop because no further socket operation was required. ### Affected usages Applications and libraries using urllib3 versions 2.6.2 through 2.7.0 may be affected when all of the following conditions are met: 1. Compressed responses from an untrusted source are streamed using HTTPResponse.stream(amt=N) or HTTPResponse.read_chunked(amt=N) with a positive, finite chunk size. 2. Content decoding is enabled. 3. The response uses both Transfer-Encoding: chunked and Content-Encoding: deflate. 4. The decoded body exceeds the requested chunk size and the encoded body contains bytes after the end of the Deflate stream. HTTPResponse.stream() uses a finite chunk size by default and is therefore affected when the other conditions are met. ### Remediation Upgrade to urllib3 2.8.0, in which the Deflate decoder stops accepting input after reaching the end of the compressed stream and no longer reports trailing bytes as data that can produce more decoded output. If upgrading is not immediately possible, disable automatic content decoding for responses from untrusted sources by setting decode_content=False, or reject streamed responses using the Deflate content encoding. Applications that disable automatic decoding must handle the compressed response safely at another layer.
urllib3	2.7.0	PYSEC-2026-4175	2.8.0	## Impact urllib3 supports configuring TLS independently for an HTTPS proxy and the target server. proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server. In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could: 1. Ignore proxy_ssl_context and use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. 2. Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy. 3. Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy. In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context. An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust or identity policy is incorrectly applied to the proxy connection. When HTTPS forwarding is enabled, an impersonated proxy can observe or modify forwarded requests and responses, potentially exposing credentials, authentication tokens, request bodies, response data, and other sensitive information. A TLS client certificate intended for the target server may also be presented to the proxy or to an attacker impersonating it. This can disclose the client's identity and provide proof of possession of the corresponding private key. The private key itself is not transmitted during the TLS handshake. In CONNECT tunneling mode, impersonating the HTTPS proxy does not by itself defeat the separate end-to-end TLS connection between the client and the target server. ## Affected Usages Code using urllib3 versions 1.26.0 through 2.7.0 may be affected in any of the following cases. ### 1. The target SSL context is used for an HTTPS forwarding proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and proxy_ssl_context is configured for the proxy. urllib3 may ignore proxy_ssl_context and use the target server's ssl_context for the proxy TLS handshake. The proxy may therefore be verified using the target server's trust and certificate policy instead of the policy explicitly configured for the proxy. ### 2. The target verification policy overrides the proxy policy An HTTPS proxy is configured with proxy_ssl_context, while the target server uses a different certificate-verification policy. urllib3 may apply the target server's cert_reqs value to the proxy SSL context. For example, setting cert_reqs="CERT_NONE" for the target server may also disable certificate verification for the HTTPS proxy, even when proxy_ssl_context was configured to require verification. This issue can affect the TLS connection to an HTTPS proxy in both forwarding and CONNECT tunneling configurations. ### 3. A mutated proxy SSL context is reused The same SSL context is reused as proxy_ssl_context across multiple connections, and certificate verification is disabled for one target server. urllib3 may modify the proxy SSL context's verify_mode in place. Later connections that reuse the same context may therefore connect to the HTTPS proxy without certificate verification. ### 4. Target-specific TLS identity or credentials are applied to the proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials are configured. urllib3 may apply these target-specific settings to the proxy TLS handshake. This may cause urllib3 to: - send SNI intended for the target server to the proxy; - verify the proxy using a hostname or certificate fingerprint intended for the target server; or - present a TLS client certificate intended for the target server to the proxy. Code connecting through a plain HTTP proxy does not establish a TLS connection to the proxy and is not affected by this issue. ## Remediation Upgrade to urllib3 2.8.0 or later. urllib3 2.8.0 independently applies the explicitly configured proxy_ssl_context and proxy-specific certificate assertions to the HTTPS proxy connection. Target-specific SNI, certificate assertions, and TLS client certificate parameters are no longer applied to the HTTPS proxy handshake. For backward compatibility, when an HTTPS proxy is used with use_forwarding_for_https=True and proxy_ssl_context is not provided, urllib3 2.8.0 continues to use ssl_context for the TLS connection to the proxy. This configuration emits a FutureWarning. In urllib3 3.0, passing ssl_context with use_forwarding_for_https=True for an HTTPS proxy will raise an error. Applications should use proxy_ssl_context to configure TLS for an HTTPS forwarding proxy. The fixes were implemented in commits b6447295fff7b38fdffc67e0df9712d60cef3cc3 and 07408cec79d1856d81bb42c74a904a24fdb9e465.

Fixed dependency issues for Python 3.12

Name	Version	ID	Fix Versions	Description
urllib3	2.7.0	PYSEC-2026-4177	2.8.0	## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees \n or EOF. A malicious HTTP server can return Transfer-Encoding: chunked and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected when streaming a chunked response from untrusted sources. Specifically, this affects the read_chunked() and stream() methods of the HTTPResponse object. This also affects requests streaming API, which uses urllib3 under the hood. ## Remediation Upgrade to urllib3 version 2.8.0 or later, where chunk-size fields larger than 65536 will be rejected. If upgrading is not immediately possible, consider reading the response at once using the read() method.
urllib3	2.7.0	PYSEC-2026-4176	2.8.0	### Impact urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading content in chunks instead of loading the entire response body into memory at once. urllib3 can decompress response bodies according to the HTTP Content-Encoding header. When streaming a compressed, chunked response, urllib3 first consumes data already buffered by the decoder before reading the next HTTP chunk. However, urllib3 versions from 2.6.2 through 2.7.0 could enter an infinite loop when a chunked response contained bytes after the end of the Deflate stream. If the decompressed body exceeded the requested streaming chunk size, Python's zlib implementation could retain the trailing bytes as unconsumed input after reaching the end of the compressed stream. urllib3 would repeatedly attempt to decode those same bytes without making progress or reading more data from the network. A malicious server could exploit this behavior to cause excessive CPU usage and prevent the affected request from completing on the client. Network read timeouts would not interrupt the loop because no further socket operation was required. ### Affected usages Applications and libraries using urllib3 versions 2.6.2 through 2.7.0 may be affected when all of the following conditions are met: 1. Compressed responses from an untrusted source are streamed using HTTPResponse.stream(amt=N) or HTTPResponse.read_chunked(amt=N) with a positive, finite chunk size. 2. Content decoding is enabled. 3. The response uses both Transfer-Encoding: chunked and Content-Encoding: deflate. 4. The decoded body exceeds the requested chunk size and the encoded body contains bytes after the end of the Deflate stream. HTTPResponse.stream() uses a finite chunk size by default and is therefore affected when the other conditions are met. ### Remediation Upgrade to urllib3 2.8.0, in which the Deflate decoder stops accepting input after reaching the end of the compressed stream and no longer reports trailing bytes as data that can produce more decoded output. If upgrading is not immediately possible, disable automatic content decoding for responses from untrusted sources by setting decode_content=False, or reject streamed responses using the Deflate content encoding. Applications that disable automatic decoding must handle the compressed response safely at another layer.
urllib3	2.7.0	PYSEC-2026-4175	2.8.0	## Impact urllib3 supports configuring TLS independently for an HTTPS proxy and the target server. proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server. In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could: 1. Ignore proxy_ssl_context and use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. 2. Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy. 3. Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy. In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context. An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust or identity policy is incorrectly applied to the proxy connection. When HTTPS forwarding is enabled, an impersonated proxy can observe or modify forwarded requests and responses, potentially exposing credentials, authentication tokens, request bodies, response data, and other sensitive information. A TLS client certificate intended for the target server may also be presented to the proxy or to an attacker impersonating it. This can disclose the client's identity and provide proof of possession of the corresponding private key. The private key itself is not transmitted during the TLS handshake. In CONNECT tunneling mode, impersonating the HTTPS proxy does not by itself defeat the separate end-to-end TLS connection between the client and the target server. ## Affected Usages Code using urllib3 versions 1.26.0 through 2.7.0 may be affected in any of the following cases. ### 1. The target SSL context is used for an HTTPS forwarding proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and proxy_ssl_context is configured for the proxy. urllib3 may ignore proxy_ssl_context and use the target server's ssl_context for the proxy TLS handshake. The proxy may therefore be verified using the target server's trust and certificate policy instead of the policy explicitly configured for the proxy. ### 2. The target verification policy overrides the proxy policy An HTTPS proxy is configured with proxy_ssl_context, while the target server uses a different certificate-verification policy. urllib3 may apply the target server's cert_reqs value to the proxy SSL context. For example, setting cert_reqs="CERT_NONE" for the target server may also disable certificate verification for the HTTPS proxy, even when proxy_ssl_context was configured to require verification. This issue can affect the TLS connection to an HTTPS proxy in both forwarding and CONNECT tunneling configurations. ### 3. A mutated proxy SSL context is reused The same SSL context is reused as proxy_ssl_context across multiple connections, and certificate verification is disabled for one target server. urllib3 may modify the proxy SSL context's verify_mode in place. Later connections that reuse the same context may therefore connect to the HTTPS proxy without certificate verification. ### 4. Target-specific TLS identity or credentials are applied to the proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials are configured. urllib3 may apply these target-specific settings to the proxy TLS handshake. This may cause urllib3 to: - send SNI intended for the target server to the proxy; - verify the proxy using a hostname or certificate fingerprint intended for the target server; or - present a TLS client certificate intended for the target server to the proxy. Code connecting through a plain HTTP proxy does not establish a TLS connection to the proxy and is not affected by this issue. ## Remediation Upgrade to urllib3 2.8.0 or later. urllib3 2.8.0 independently applies the explicitly configured proxy_ssl_context and proxy-specific certificate assertions to the HTTPS proxy connection. Target-specific SNI, certificate assertions, and TLS client certificate parameters are no longer applied to the HTTPS proxy handshake. For backward compatibility, when an HTTPS proxy is used with use_forwarding_for_https=True and proxy_ssl_context is not provided, urllib3 2.8.0 continues to use ssl_context for the TLS connection to the proxy. This configuration emits a FutureWarning. In urllib3 3.0, passing ssl_context with use_forwarding_for_https=True for an HTTPS proxy will raise an error. Applications should use proxy_ssl_context to configure TLS for an HTTPS forwarding proxy. The fixes were implemented in commits b6447295fff7b38fdffc67e0df9712d60cef3cc3 and 07408cec79d1856d81bb42c74a904a24fdb9e465.

Fixed dependency issues for Python 3.13

Name	Version	ID	Fix Versions	Description
urllib3	2.7.0	PYSEC-2026-4177	2.8.0	## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees \n or EOF. A malicious HTTP server can return Transfer-Encoding: chunked and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected when streaming a chunked response from untrusted sources. Specifically, this affects the read_chunked() and stream() methods of the HTTPResponse object. This also affects requests streaming API, which uses urllib3 under the hood. ## Remediation Upgrade to urllib3 version 2.8.0 or later, where chunk-size fields larger than 65536 will be rejected. If upgrading is not immediately possible, consider reading the response at once using the read() method.
urllib3	2.7.0	PYSEC-2026-4176	2.8.0	### Impact urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading content in chunks instead of loading the entire response body into memory at once. urllib3 can decompress response bodies according to the HTTP Content-Encoding header. When streaming a compressed, chunked response, urllib3 first consumes data already buffered by the decoder before reading the next HTTP chunk. However, urllib3 versions from 2.6.2 through 2.7.0 could enter an infinite loop when a chunked response contained bytes after the end of the Deflate stream. If the decompressed body exceeded the requested streaming chunk size, Python's zlib implementation could retain the trailing bytes as unconsumed input after reaching the end of the compressed stream. urllib3 would repeatedly attempt to decode those same bytes without making progress or reading more data from the network. A malicious server could exploit this behavior to cause excessive CPU usage and prevent the affected request from completing on the client. Network read timeouts would not interrupt the loop because no further socket operation was required. ### Affected usages Applications and libraries using urllib3 versions 2.6.2 through 2.7.0 may be affected when all of the following conditions are met: 1. Compressed responses from an untrusted source are streamed using HTTPResponse.stream(amt=N) or HTTPResponse.read_chunked(amt=N) with a positive, finite chunk size. 2. Content decoding is enabled. 3. The response uses both Transfer-Encoding: chunked and Content-Encoding: deflate. 4. The decoded body exceeds the requested chunk size and the encoded body contains bytes after the end of the Deflate stream. HTTPResponse.stream() uses a finite chunk size by default and is therefore affected when the other conditions are met. ### Remediation Upgrade to urllib3 2.8.0, in which the Deflate decoder stops accepting input after reaching the end of the compressed stream and no longer reports trailing bytes as data that can produce more decoded output. If upgrading is not immediately possible, disable automatic content decoding for responses from untrusted sources by setting decode_content=False, or reject streamed responses using the Deflate content encoding. Applications that disable automatic decoding must handle the compressed response safely at another layer.
urllib3	2.7.0	PYSEC-2026-4175	2.8.0	## Impact urllib3 supports configuring TLS independently for an HTTPS proxy and the target server. proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server. In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could: 1. Ignore proxy_ssl_context and use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. 2. Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy. 3. Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy. In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context. An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust or identity policy is incorrectly applied to the proxy connection. When HTTPS forwarding is enabled, an impersonated proxy can observe or modify forwarded requests and responses, potentially exposing credentials, authentication tokens, request bodies, response data, and other sensitive information. A TLS client certificate intended for the target server may also be presented to the proxy or to an attacker impersonating it. This can disclose the client's identity and provide proof of possession of the corresponding private key. The private key itself is not transmitted during the TLS handshake. In CONNECT tunneling mode, impersonating the HTTPS proxy does not by itself defeat the separate end-to-end TLS connection between the client and the target server. ## Affected Usages Code using urllib3 versions 1.26.0 through 2.7.0 may be affected in any of the following cases. ### 1. The target SSL context is used for an HTTPS forwarding proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and proxy_ssl_context is configured for the proxy. urllib3 may ignore proxy_ssl_context and use the target server's ssl_context for the proxy TLS handshake. The proxy may therefore be verified using the target server's trust and certificate policy instead of the policy explicitly configured for the proxy. ### 2. The target verification policy overrides the proxy policy An HTTPS proxy is configured with proxy_ssl_context, while the target server uses a different certificate-verification policy. urllib3 may apply the target server's cert_reqs value to the proxy SSL context. For example, setting cert_reqs="CERT_NONE" for the target server may also disable certificate verification for the HTTPS proxy, even when proxy_ssl_context was configured to require verification. This issue can affect the TLS connection to an HTTPS proxy in both forwarding and CONNECT tunneling configurations. ### 3. A mutated proxy SSL context is reused The same SSL context is reused as proxy_ssl_context across multiple connections, and certificate verification is disabled for one target server. urllib3 may modify the proxy SSL context's verify_mode in place. Later connections that reuse the same context may therefore connect to the HTTPS proxy without certificate verification. ### 4. Target-specific TLS identity or credentials are applied to the proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials are configured. urllib3 may apply these target-specific settings to the proxy TLS handshake. This may cause urllib3 to: - send SNI intended for the target server to the proxy; - verify the proxy using a hostname or certificate fingerprint intended for the target server; or - present a TLS client certificate intended for the target server to the proxy. Code connecting through a plain HTTP proxy does not establish a TLS connection to the proxy and is not affected by this issue. ## Remediation Upgrade to urllib3 2.8.0 or later. urllib3 2.8.0 independently applies the explicitly configured proxy_ssl_context and proxy-specific certificate assertions to the HTTPS proxy connection. Target-specific SNI, certificate assertions, and TLS client certificate parameters are no longer applied to the HTTPS proxy handshake. For backward compatibility, when an HTTPS proxy is used with use_forwarding_for_https=True and proxy_ssl_context is not provided, urllib3 2.8.0 continues to use ssl_context for the TLS connection to the proxy. This configuration emits a FutureWarning. In urllib3 3.0, passing ssl_context with use_forwarding_for_https=True for an HTTPS proxy will raise an error. Applications should use proxy_ssl_context to configure TLS for an HTTPS forwarding proxy. The fixes were implemented in commits b6447295fff7b38fdffc67e0df9712d60cef3cc3 and 07408cec79d1856d81bb42c74a904a24fdb9e465.

Fixed dependency issues for Python 3.14

Name	Version	ID	Fix Versions	Description
urllib3	2.7.0	PYSEC-2026-4177	2.8.0	## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees \n or EOF. A malicious HTTP server can return Transfer-Encoding: chunked and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected when streaming a chunked response from untrusted sources. Specifically, this affects the read_chunked() and stream() methods of the HTTPResponse object. This also affects requests streaming API, which uses urllib3 under the hood. ## Remediation Upgrade to urllib3 version 2.8.0 or later, where chunk-size fields larger than 65536 will be rejected. If upgrading is not immediately possible, consider reading the response at once using the read() method.
urllib3	2.7.0	PYSEC-2026-4176	2.8.0	### Impact urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading content in chunks instead of loading the entire response body into memory at once. urllib3 can decompress response bodies according to the HTTP Content-Encoding header. When streaming a compressed, chunked response, urllib3 first consumes data already buffered by the decoder before reading the next HTTP chunk. However, urllib3 versions from 2.6.2 through 2.7.0 could enter an infinite loop when a chunked response contained bytes after the end of the Deflate stream. If the decompressed body exceeded the requested streaming chunk size, Python's zlib implementation could retain the trailing bytes as unconsumed input after reaching the end of the compressed stream. urllib3 would repeatedly attempt to decode those same bytes without making progress or reading more data from the network. A malicious server could exploit this behavior to cause excessive CPU usage and prevent the affected request from completing on the client. Network read timeouts would not interrupt the loop because no further socket operation was required. ### Affected usages Applications and libraries using urllib3 versions 2.6.2 through 2.7.0 may be affected when all of the following conditions are met: 1. Compressed responses from an untrusted source are streamed using HTTPResponse.stream(amt=N) or HTTPResponse.read_chunked(amt=N) with a positive, finite chunk size. 2. Content decoding is enabled. 3. The response uses both Transfer-Encoding: chunked and Content-Encoding: deflate. 4. The decoded body exceeds the requested chunk size and the encoded body contains bytes after the end of the Deflate stream. HTTPResponse.stream() uses a finite chunk size by default and is therefore affected when the other conditions are met. ### Remediation Upgrade to urllib3 2.8.0, in which the Deflate decoder stops accepting input after reaching the end of the compressed stream and no longer reports trailing bytes as data that can produce more decoded output. If upgrading is not immediately possible, disable automatic content decoding for responses from untrusted sources by setting decode_content=False, or reject streamed responses using the Deflate content encoding. Applications that disable automatic decoding must handle the compressed response safely at another layer.
urllib3	2.7.0	PYSEC-2026-4175	2.8.0	## Impact urllib3 supports configuring TLS independently for an HTTPS proxy and the target server. proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server. In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could: 1. Ignore proxy_ssl_context and use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. 2. Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy. 3. Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy. In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context. An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust or identity policy is incorrectly applied to the proxy connection. When HTTPS forwarding is enabled, an impersonated proxy can observe or modify forwarded requests and responses, potentially exposing credentials, authentication tokens, request bodies, response data, and other sensitive information. A TLS client certificate intended for the target server may also be presented to the proxy or to an attacker impersonating it. This can disclose the client's identity and provide proof of possession of the corresponding private key. The private key itself is not transmitted during the TLS handshake. In CONNECT tunneling mode, impersonating the HTTPS proxy does not by itself defeat the separate end-to-end TLS connection between the client and the target server. ## Affected Usages Code using urllib3 versions 1.26.0 through 2.7.0 may be affected in any of the following cases. ### 1. The target SSL context is used for an HTTPS forwarding proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and proxy_ssl_context is configured for the proxy. urllib3 may ignore proxy_ssl_context and use the target server's ssl_context for the proxy TLS handshake. The proxy may therefore be verified using the target server's trust and certificate policy instead of the policy explicitly configured for the proxy. ### 2. The target verification policy overrides the proxy policy An HTTPS proxy is configured with proxy_ssl_context, while the target server uses a different certificate-verification policy. urllib3 may apply the target server's cert_reqs value to the proxy SSL context. For example, setting cert_reqs="CERT_NONE" for the target server may also disable certificate verification for the HTTPS proxy, even when proxy_ssl_context was configured to require verification. This issue can affect the TLS connection to an HTTPS proxy in both forwarding and CONNECT tunneling configurations. ### 3. A mutated proxy SSL context is reused The same SSL context is reused as proxy_ssl_context across multiple connections, and certificate verification is disabled for one target server. urllib3 may modify the proxy SSL context's verify_mode in place. Later connections that reuse the same context may therefore connect to the HTTPS proxy without certificate verification. ### 4. Target-specific TLS identity or credentials are applied to the proxy HTTPS requests are forwarded through an HTTPS proxy with use_forwarding_for_https=True, and target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials are configured. urllib3 may apply these target-specific settings to the proxy TLS handshake. This may cause urllib3 to: - send SNI intended for the target server to the proxy; - verify the proxy using a hostname or certificate fingerprint intended for the target server; or - present a TLS client certificate intended for the target server to the proxy. Code connecting through a plain HTTP proxy does not establish a TLS connection to the proxy and is not affected by this issue. ## Remediation Upgrade to urllib3 2.8.0 or later. urllib3 2.8.0 independently applies the explicitly configured proxy_ssl_context and proxy-specific certificate assertions to the HTTPS proxy connection. Target-specific SNI, certificate assertions, and TLS client certificate parameters are no longer applied to the HTTPS proxy handshake. For backward compatibility, when an HTTPS proxy is used with use_forwarding_for_https=True and proxy_ssl_context is not provided, urllib3 2.8.0 continues to use ssl_context for the TLS connection to the proxy. This configuration emits a FutureWarning. In urllib3 3.0, passing ssl_context with use_forwarding_for_https=True for an HTTPS proxy will raise an error. Applications should use proxy_ssl_context to configure TLS for an HTTPS forwarding proxy. The fixes were implemented in commits b6447295fff7b38fdffc67e0df9712d60cef3cc3 and 07408cec79d1856d81bb42c74a904a24fdb9e465.

Dependency issues not solved for Python 3.9

Name	Version	ID	Fix Versions	Description
pillow	11.3.0	PYSEC-2026-165	12.2.0	Pillow is a Python imaging library. Prior to version 12.2.0, if a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This issue has been patched in version 12.2.0.
pillow	11.3.0	PYSEC-2026-2250	12.2.0	Pillow is a Python imaging library. Versions 10.3.0 through 12.1.1 did not limit the amount of GZIP-compressed data read when decoding a FITS image, making them vulnerable to decompression bomb attacks. A specially crafted FITS file could cause unbounded memory consumption, leading to denial of service (OOM crash or severe performance degradation). If users are unable to immediately upgrade, they should only open specific image formats, excluding FITS, as a workaround.
pillow	11.3.0	PYSEC-2026-2253	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, PIL/PcfFontFile.py _load_bitmaps() read glyph dimensions from the PCF METRICS section and passed them directly to Image.frombytes() without calling Image._decompression_bomb_check(), allowing crafted PCF font data to cause excessive memory allocation. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-2251	12.2.0	Pillow is a Python imaging library. From version 11.2.1 to before version 12.2.0, passing nested lists as coordinates to APIs that accept coordinates such as ImagePath.Path, ImageDraw.ImageDraw.polygon and ImageDraw.ImageDraw.line could cause a heap buffer overflow, as nested lists were recursively unpacked beyond the allocated buffer. Coordinate lists are now validated to contain exactly two numeric coordinates. This issue has been patched in version 12.2.0.
pillow	11.3.0	PYSEC-2026-2255	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, PIL/BdfFontFile.py bdf_char() read the BBX width and height field from a BDF font file and passed attacker-controlled dimensions to Image.new() without calling Image._decompression_bomb_check(), bypassing Pillow's documented decompression bomb protection and allowing excessive memory allocation. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-2257	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, WindowsViewer.get_command() constructed a cmd.exe shell command by directly embedding a file path into an f-string without escaping and passed the result to subprocess.Popen(..., shell=True), allowing shell metacharacters in the file path to inject arbitrary cmd.exe commands. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-2256	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, PIL/GdImageFile.py GdImageFile._open() read image dimensions from the GD 2.x header and stored them in self._size without calling Image._decompression_bomb_check(), allowing a crafted .gd file to trigger excessive C-heap allocation when loaded. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-2254	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, PIL/FontFile.py FontFile.compile() assembled per-glyph images into a combined bitmap with Image.new("1", (xsize, ysize)) without calling Image._decompression_bomb_check(), allowing a font to trigger excessive allocation during conversion or saving. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-2252	12.2.0	Pillow is a Python imaging library. From version 10.3.0 to before version 12.2.0, processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. This issue has been patched in version 12.2.0.
pillow	11.3.0	PYSEC-2026-2249	12.1.1	Pillow is a Python imaging library. From 10.3.0 to before 12.1.1, an out-of-bounds write may be triggered when loading a specially crafted PSD image. This vulnerability is fixed in 12.1.1.
pillow	11.3.0	PYSEC-2026-2874	12.2.0	### Impact An attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive. ### Patches Patched version: 12.2.0. PdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a trailer's Prev pointer references an offset that has already been processed — either pointing to itself or forming a longer cycle — the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an error if a cycle is detected. ### Workarounds Use any version but the affected versions: >= 4.2.0, < 12.2.0 ### Resources - Fix: python-pillow/Pillow#9519
pillow	11.3.0	PYSEC-2026-3453	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-3451	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-3454	12.3.0	Pillow is a Python imaging library. Prior to 12.3.0, Pillow's public rank-filter API can trigger a native heap out-of-bounds write when given a very large odd filter size because ImageFilter.RankFilter.filter() calls image.expand(size // 2, size // 2) before rank-filter size validation and ImagingExpand() computes output dimensions with unchecked signed int arithmetic. This issue is fixed in version 12.3.0.
pillow	11.3.0	PYSEC-2026-3495	12.3.0	### Summary PdfParser.PdfStream.decode() in Pillow's PdfParser.py calls zlib.decompress() with the bufsize parameter set to the value of the PDF stream's Length field, without any upper bound on the actual decompressed output size. Python's zlib.decompress() bufsize argument is an initial output buffer hint, not a maximum size limit — the function will expand memory until the full decompressed result is produced. A crafted PDF containing a FlateDecode-compressed stream decompresses to 1 GB of memory from a ~950 KB file, causing server OOM termination or severe degradation in any application that uses PdfParser to read untrusted PDF files. ### Details PdfStream.decode() in pdfminer/PdfParser.py reads the stream's declared Length (or DL) field from the PDF dictionary and passes it as bufsize to zlib.decompress(): python # PIL/PdfParser.py — PdfStream.decode() class PdfStream: def decode(self) -> bytes: try: filter = self.dictionary[b"Filter"] except KeyError: return self.buf if filter == b"FlateDecode": try: expected_length = self.dictionary[b"DL"] except KeyError: expected_length = self.dictionary[b"Length"] return zlib.decompress(self.buf, bufsize=int(expected_length)) # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ # bufsize is an *initial buffer hint*, NOT a maximum size limit. # zlib.decompress() allocates as much memory as needed regardless. From the Python documentation: "The bufsize parameter is used as the initial size of the output buffer." It does not cap decompression. An attacker who controls the PDF stream contents can provide a highly-compressed payload that expands to gigabytes, while setting Length to any value (including the actual compressed size) to avoid triggering format validation. PdfParser is instantiated with a filename or file object and calls read_pdf_info() on open, which parses the xref table and makes stream objects accessible. PdfStream.decode() is reachable whenever calling code accesses a compressed stream object from the parsed PDF. Confirmed reachable path: python with PdfParser.PdfParser("evil.pdf") as pdf: stream_obj, _ = pdf.get_value(pdf.buf, stream_offset) data = stream_obj.decode() # ← OOM here ### PoC python import zlib, tempfile, os, time from PIL import PdfParser # Build a minimal PDF with a 100 MB FlateDecode bomb (demo scale) EXPAND_MB = 100 raw = b'\x00' * (EXPAND_MB * 1_000_000) compressed = zlib.compress(raw, level=9) # ~97 KB buf = b'%PDF-1.4\n' o1 = len(buf); buf += b'1 0 obj\n<< /Type /Pages /Kids [] /Count 0 >>\nendobj\n' o2 = len(buf); buf += b'2 0 obj\n<< /Type /Catalog /Pages 1 0 R >>\nendobj\n' o3 = len(buf) hdr = f'<< /Filter /FlateDecode /Length {len(compressed)} >>'.encode() buf += b'3 0 obj\n' + hdr + b'\nstream\n' + compressed + b'\nendstream\nendobj\n' xref = len(buf) buf += b'xref\n0 4\n0000000000 65535 f \n' for off in [o1, o2, o3]: buf += f'{off:010d} 00000 n \n'.encode() buf += b'trailer\n<< /Size 4 /Root 2 0 R >>\nstartxref\n' + str(xref).encode() + b'\n%%EOF\n' print(f"PDF size: {len(buf):,} bytes ({len(buf)/1024:.1f} KB)") with tempfile.NamedTemporaryFile(delete=False, suffix='.pdf') as f: f.write(buf); tmpname = f.name with PdfParser.PdfParser(tmpname) as pdf: obj, _ = pdf.get_value(pdf.buf, o3) t = time.time() decoded = obj.decode() print(f"Decoded: {len(decoded):,} bytes in {time.time()-t:.3f}s") os.unlink(tmpname) Actual output (Pillow 12.1.1, Python 3.12): PDF size: 97,538 bytes (95.3 KB) Decoded: 100,000,000 bytes in 0.265s Measured expansion:
pillow	11.3.0	PYSEC-2026-3496	12.3.0	### Summary src/libImaging/Jpeg2KDecode.c:853 accumulates total_component_width across every tile in a JPEG2000 image instead of recomputing it per tile. That accumulated value is then used in the tile_bytes calculation at src/libImaging/Jpeg2KDecode.c:868, which can make the decoder grow state->buffer via realloc at src/libImaging/Jpeg2KDecode.c:876 up to roughly one full image's decompressed size even when each tile is small. A crafted tiled JPEG2000 file can therefore force substantially higher transient memory usage and trigger out-of-memory failures during decoding. Based on current evidence, the supported impact is denial of service, not memory corruption. ### Details - Location: src/libImaging/Jpeg2KDecode.c:853 - Root cause: total_component_width is initialized only once before the tile loop and keeps growing across tiles. It is then used to derive tile_bytes, so later tiles are treated as if they had the combined component width of all earlier tiles. - Dangerous operation: tile_bytes is promoted into tile_info.data_size, then state->buffer is grown with realloc at src/libImaging/Jpeg2KDecode.c:876. - Reachability: any attacker-controlled JPEG2000 image with many tiles reaches this path during normal Image.open(...).load() decoding. ### PoC The attached helper script and testcase were used: exercise_j2k_tile_realloc.zip Generate the testcase: bash pythonexercise_j2k_tile_realloc.py make poc_3664_rgba_tile1832.jp2 \ --size 3664 --tile 1832 Expected geometry from the helper: - image size: 3664 x 3664 - mode: RGBA - tile size: 1832 x 1832 (2x2 tiles) - image_bytes=53699584 - uncapped RSS observed: - vulnerable build: maxrss_kb=180264 - fixed comparison build: maxrss_kb=138404 Load it with the current vulnerable build: bash python exercise_j2k_tile_realloc.py load poc_3664_rgba_tile1832.jp2 Load it again under a 160 MB address-space cap: bash python exercise_j2k_tile_realloc.py load poc_3664_rgba_tile1832.jp2 --limit-mb 160 ### Impact Conservative impact: denial of service through memory exhaust