Update dependency urllib3 to v2.6.3 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
urllib3 (changelog)	==2.6.0 → ==2.6.3

GitHub Vulnerability Alerts

CVE-2026-21441

Impact

urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once.

urllib3 can perform decoding or decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd). When using the streaming API, the library decompresses only the necessary bytes, enabling partial content consumption.

However, for HTTP redirect responses, the library would read the entire response body to drain the connection and decompress the content unnecessarily. This decompression occurred even before any read methods were called, and configured read limits did not restrict the amount of decompressed data. As a result, there was no safeguard against decompression bombs. A malicious server could exploit this to trigger excessive resource consumption on the client (high CPU usage and large memory allocations for decompressed data; CWE-409).

Affected usages

Applications and libraries using urllib3 version 2.6.2 and earlier to stream content from untrusted sources by setting preload_content=False when they do not disable redirects.

Remediation

Upgrade to at least urllib3 v2.6.3 in which the library does not decode content of redirect responses when preload_content=False.

If upgrading is not immediately possible, disable redirects by setting redirect=False for requests to untrusted source.

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Release Notes

urllib3/urllib3 (urllib3)

v2.6.3

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

• Fixed a high-severity security issue where decompression-bomb safeguards of
  the streaming API were bypassed when HTTP redirects were followed.
  (GHSA-38jv-5279-wg99 <https://github.com/urllib3/urllib3/security/advisories/GHSA-38jv-5279-wg99>__)
• Started treating Retry-After times greater than 6 hours as 6 hours by
  default. (#&#8203;3743 <https://github.com/urllib3/urllib3/issues/3743>__)
• Fixed urllib3.connection.VerifiedHTTPSConnection on Emscripten.
  (#&#8203;3752 <https://github.com/urllib3/urllib3/issues/3752>__)

v2.6.2

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

• Fixed HTTPResponse.read_chunked() to properly handle leftover data in
  the decoder's buffer when reading compressed chunked responses.
  (#&#8203;3734 <https://github.com/urllib3/urllib3/issues/3734>__)

v2.6.1

Compare Source

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

• Restore previously removed HTTPResponse.getheaders() and
  HTTPResponse.getheader() methods.
  (#&#8203;3731 <https://github.com/urllib3/urllib3/issues/3731>__)

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