Skip to content

Conversation

@renovate-bot
Copy link
Contributor

@renovate-bot 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

Warning

Some dependencies could not be looked up. Check the Dependency Dashboard for more information.

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 - "" (UTC), 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-bot renovate-bot requested review from a team as code owners January 8, 2026 06:45
@trusted-contributions-gcf trusted-contributions-gcf bot added the owlbot:run Add this label to trigger the Owlbot post processor. label Jan 8, 2026
@gcf-owl-bot gcf-owl-bot bot removed the owlbot:run Add this label to trigger the Owlbot post processor. label Jan 8, 2026
@bshaffer bshaffer merged commit 19dccdb into googleapis:main Jan 8, 2026
36 checks passed
@renovate-bot renovate-bot deleted the renovate/pypi-urllib3-vulnerability branch January 8, 2026 15:19
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants