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@renovate renovate bot commented Jan 8, 2026

This PR contains the following updates:

Package Change Age Confidence
urllib3 (changelog) ==2.6.0==2.6.3 age confidence

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.


Release Notes

urllib3/urllib3 (urllib3)

v2.6.3

Compare Source

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

  • 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

Compare Source

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

  • 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>__)

Configuration

📅 Schedule: Branch creation - "" in timezone Europe/Berlin, Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.


  • If you want to rebase/retry this PR, check this box

This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate bot force-pushed the renovate/pypi-urllib3-vulnerability branch from 160a97b to cb8b56d Compare January 13, 2026 10:49
@renovate renovate bot force-pushed the renovate/pypi-urllib3-vulnerability branch 2 times, most recently from 5fc322d to 1796640 Compare January 27, 2026 20:25
@renovate renovate bot force-pushed the renovate/pypi-urllib3-vulnerability branch 2 times, most recently from 8e35b23 to c59cf8c Compare February 6, 2026 08:59
@renovate renovate bot force-pushed the renovate/pypi-urllib3-vulnerability branch from c59cf8c to 92a42ff Compare February 6, 2026 11:59
@tamang29 tamang29 merged commit b98873c into main Feb 6, 2026
3 checks passed
@tamang29 tamang29 deleted the renovate/pypi-urllib3-vulnerability branch February 6, 2026 21:10
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