Sourced from urllib3's releases.

2.8.0

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Security

Fixed the following security issues:

• The TLS configuration for HTTPS proxies could be ignored or overridden. (High severity, GHSA-8988-9cw3-xx77)
• HTTPResponse.stream() and read_chunked() could buffer a chunk-size line of unbounded length in memory. (High severity, GHSA-vxq7-64xx-v4gw)
• Chunked Deflate streaming could enter an infinite loop. (Medium severity, GHSA-gh4c-6fx4-qh6g)

[!IMPORTANT] urllib3 2.8.0 fixes HTTPS proxy TLS configuration being ignored or overridden by destination settings. Configurations relying on that behavior may require changes.

Configure proxy CA certificates and client certificates in proxy_ssl_context, and proxy identity checks with proxy_assert_hostname or proxy_assert_fingerprint. Destination client certificates and identity overrides no longer apply to HTTPS forwarding proxy connections.

[!NOTE] CVE IDs had not yet been assigned to these advisories at the time of release due to a backlog at GitHub's CNA.

Deprecations & Removals

• Deprecated using an empty collection as the Retry option allowed_methods to retry any verb. (#5044)

Features

• Added Url.auth_decoded and Url.auth_decoded_joined convenience properties to the result of parse_url(). (#4945)
• Added basic_auth_encoding and proxy_basic_auth_encoding parameters to urllib3.util.make_headers(). (#5092)

Bugfixes

• Fixed response header handling to replace obsolete folded header lines (obs-fold) with spaces in accordance with RFC 9112, preventing raw CRLF sequences from appearing in header values such as Set-Cookie. (#1362)

• Fixed usage of proxy_ssl_context with ProxyManager when use_forwarding_for_https=True. Passing ssl_context instead of proxy_ssl_context for HTTPS proxies in this configuration now emits a FutureWarning and will raise an error in v3.0. (#2577)

• Changed behavior of the default ConnectionPool.pool initialization. LifoQueue is now resolved from the queue module after the ConnectionPool is instantiated instead of using the default cached QueueCls class property. This is done because sometimes the queue.LifoQueue is monkey-patched late in the program, such as by gevent. (#3289)

• Raised UnrewindableBodyError instead of ValueError when retrying a request whose body had tell() but not seek(). (#3779)

• Decoded percent-encoded SOCKS proxy credentials before authenticating with the proxy server. (#3785)

• Fixed HTTPResponse.drain_conn() to discard unread response data in 64 KiB chunks (same as the default amt when doing HTTPResponse.stream(...)). (#5019)

• Fixed is_ipaddress() to detect non-standard IPv4 forms accepted by socket.connect, such as hex (0x7f000001), octal (0177.0.0.1), and decimal integers (2130706433), ensuring SSL certificate verification uses the correct mode for these addresses. (#5029)

• Fixed HTTPConnectionPool.urlopen raising a misleading FullPoolError instead of ValueError when called with an invalid timeout argument on a pool created with block=True. (#5059)

• Fixed port-zero handling to preserve explicit :0 values instead of substituting the default ports 80 or 443 in URL parsing, pool selection, proxy configuration, connection_from_url(), and HTTP/2 request authority. (#5071, #5101)

• Fixed a bug where PoolManager passed the assert_hostname and assert_fingerprint parameters to HTTP connection pools. (#5077)

• Fixed HTTPConnectionPool.urlopen() and HTTP proxy forwarding to strip URL fragments from absolute request targets before sending requests. (#5079)

• Added safeguards to the proxy tunneling code to prevent potential security issues when handling invalid characters in the proxy host and HTTP headers. This change affects users of Python 3.10, Python 3.11, and Python 3.12 when the standard library does not contain the fix; those on newer Python versions should upgrade to 3.13.14+ or 3.14.5+ to get the same security fixes. (#5091)

• Fixed HTTPSConnection.connect() overriding ProxyConfig.ssl_context's certificate policy and proxy identity checks with the target connection's TLS settings when forwarding through an HTTPS proxy.

  HTTPSConnection no longer applies target SNI, assertions, or client credentials to forwarding proxy handshakes and continues to use its ssl_context as a fallback when an HTTPS proxy forwards an HTTP target. (#5093)

• Fixed URL parsing to more strictly enforce RFC 3986 host syntax, rejecting invalid host input such as raw spaces and control characters, malformed percent-encodings, and percent-encoded control characters in HTTP(S) hosts and IPv6 zone identifiers, including proxy CONNECT tunnel targets. Host normalization now also follows RFC 3986 normalization rules for percent-encoded octets by decoding percent-encoded unreserved characters and uppercasing the hexadecimal digits of retained percent-encoded octets. (#5095)

... (truncated)

Sourced from urllib3's changelog.

2.8.0 (2026-09-15)

Security

Fixed the following security issues:

• The TLS configuration for HTTPS proxies could be ignored or overridden. (High severity, GHSA-8988-9cw3-xx77 <https://github.com/urllib3/urllib3/security/advisories/GHSA-8988-9cw3-xx77>__)
• HTTPResponse.stream() and read_chunked() could buffer a chunk-size line of unbounded length in memory. (High severity, GHSA-vxq7-64xx-v4gw <https://github.com/urllib3/urllib3/security/advisories/GHSA-vxq7-64xx-v4gw>__)
• Chunked Deflate streaming could enter an infinite loop. (Medium severity, GHSA-gh4c-6fx4-qh6g <https://github.com/urllib3/urllib3/security/advisories/GHSA-gh4c-6fx4-qh6g>__)

.. caution::

urllib3 2.8.0 fixes HTTPS proxy TLS configuration being ignored or
overridden by destination settings. Configurations relying on that
behavior may require changes.
Configure proxy CA certificates and client certificates in
proxy_ssl_context, and proxy identity checks with
proxy_assert_hostname or proxy_assert_fingerprint.
Destination client certificates and identity overrides no longer
apply to HTTPS forwarding proxy connections.

Deprecations & Removals

• Deprecated using an empty collection as the Retry option allowed_methods to retry any verb. ([#5044](https://github.com/urllib3/urllib3/issues/5044) <https://github.com/urllib3/urllib3/issues/5044>__)

Features

• Added Url.auth_decoded and Url.auth_decoded_joined convenience properties to the result of parse_url(). ([#4945](https://github.com/urllib3/urllib3/issues/4945) <https://github.com/urllib3/urllib3/issues/4945>__)
• Added basic_auth_encoding and proxy_basic_auth_encoding parameters to urllib3.util.make_headers(). ([#5092](https://github.com/urllib3/urllib3/issues/5092) <https://github.com/urllib3/urllib3/issues/5092>__)

Bugfixes

... (truncated)

• b1d30ab Release 2.8.0
• 9016d7e Skip test_read_chunked_with_trailing_data_does_not_hang for brotlicffi (#5258)
• 9101f58 Fix nox -s docs warning (#5256)
• cd770b0 Merge commit from fork
• ea2ad7b Merge commit from fork
• 0716e31 Fix loading unencrypted client keys with a password in pyOpenSSL (#5255)
• 43c68c8 Test pickling of InvalidChunkLength (#5247)
• 308b279 Share security policy between GitHub and Read the Docs (#5253)
• 53fa073 Add policy on duplicate pull requests (#5252)
• 5f2a6a8 Assert on the ALPN extension in test_tunnel_sets_http_11_alpn (#5232)
• Additional commits viewable in compare view