Update dependency urllib3 to >=2.8.0, <=2.8.0 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
urllib3 (changelog)	>=2.7.0, <=2.7.0 → >=2.8.0, <=2.8.0

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urllib3: Chunked Deflate streaming can enter an infinite loop

CVE-2026-97688 / GHSA-gh4c-6fx4-qh6g

More information

Details

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.

Severity

• CVSS Score: 6.9 / 10 (Medium)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References

• https://github.com/urllib3/urllib3/security/advisories/GHSA-gh4c-6fx4-qh6g
• https://nvd.nist.gov/vuln/detail/CVE-2026-97688
• https://github.com/urllib3/urllib3/commit/ea2ad7b21a80da3632f80016526a18864586077f
• https://github.com/urllib3/urllib3/releases/tag/2.8.0
• https://github.com/advisories/GHSA-gh4c-6fx4-qh6g

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

urllib3/urllib3 (urllib3)

v2.8.0

Compare Source

==================

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.
  (#&#8203;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().
  (#&#8203;4945 <https://github.com/urllib3/urllib3/issues/4945>__)
• Added basic_auth_encoding and proxy_basic_auth_encoding parameters to
  urllib3.util.make_headers().
  (#&#8203;5092 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;1362 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;2577 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;3289 <https://github.com/urllib3/urllib3/issues/3289>__)

• Raised UnrewindableBodyError instead of ValueError when retrying a
  request whose body had tell() but not seek().
  (#&#8203;3779 <https://github.com/urllib3/urllib3/issues/3779>__)

• Decoded percent-encoded SOCKS proxy credentials before authenticating with
  the proxy server.
  (#&#8203;3785 <https://github.com/urllib3/urllib3/issues/3785>__)

• Fixed HTTPResponse.drain_conn() to discard unread response data in 64 KiB
  chunks (same as the default amt when doing HTTPResponse.stream(...)).
  (#&#8203;5019 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5029 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5059 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5071 <https://github.com/urllib3/urllib3/issues/5071>,
  #&#8203;5101 <https://github.com/urllib3/urllib3/issues/5101>)

• Fixed a bug where PoolManager passed the assert_hostname and
  assert_fingerprint parameters to HTTP connection pools.
  (#&#8203;5077 <https://github.com/urllib3/urllib3/issues/5077>__)

• Fixed HTTPConnectionPool.urlopen() and HTTP proxy forwarding to strip URL
  fragments from absolute request targets before sending requests.
  (#&#8203;5079 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5091 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5093 <https://github.com/urllib3/urllib3/issues/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.
  (#&#8203;5095 <https://github.com/urllib3/urllib3/issues/5095>__)

• Fixed an AttributeError on Python built with OpenSSL 4+, where
  ssl.PROTOCOL_TLSv1 no longer exists.
  (#&#8203;5097 <https://github.com/urllib3/urllib3/issues/5097>__)

• Fixed urllib3.contrib.pyopenssl to use cryptography APIs when reading a
  certificate subject and loading encrypted private keys, avoiding
  DeprecationWarning raised by pyOpenSSL 26.3.0+.
  (#&#8203;5103 <https://github.com/urllib3/urllib3/issues/5103>__)

• Fixed handling of HTTP 303 redirects for requests with chunked or file-like
  bodies.
  (#&#8203;5161 <https://github.com/urllib3/urllib3/issues/5161>__)

• Fixed assert_fingerprint() to raise SSLError instead of
  binascii.Error when a fingerprint has a supported length but contains
  non-hexadecimal characters.
  (#&#8203;5211 <https://github.com/urllib3/urllib3/issues/5211>__)

Misc

• Added a test dependency group containing the minimum dependencies needed
  to run the test suite, intended for downstream packagers. The dev-base
  and mypy groups now include this new group via include-group,
  removing duplication.
  (#&#8203;3594 <https://github.com/urllib3/urllib3/issues/3594>__)
• Fixed test failures with pytest >= 9.1.
  (#&#8203;5094 <https://github.com/urllib3/urllib3/issues/5094>__)
• Enabled JSPI tests with Firefox in the Emscripten test suite.
  (#&#8203;5166 <https://github.com/urllib3/urllib3/issues/5166>__)
• Improved streamed response decoding performance.
  (#&#8203;5209 <https://github.com/urllib3/urllib3/issues/5209>__)
• Fixed flaky tests.
  (#&#8203;5232 <https://github.com/urllib3/urllib3/issues/5232>,
  #&#8203;5234 <https://github.com/urllib3/urllib3/issues/5234>,
  #&#8203;5239 <https://github.com/urllib3/urllib3/issues/5239>__)

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