Hi,

The following vulnerability was published for python-urllib3.

CVE-2026-9375[0]:
| urllib3 version 2.6.3 is vulnerable to a decompression bomb bypass
| in its streaming API (`preload_content=False`) when using Brotli
| support. The issue arises due to three independent code paths in
| `response.py` that bypass the `max_length` protection introduced in
| version 2.6.0 to mitigate CVE-2025-66471. Specifically, negative
| `max_length` values can be produced due to buffer arithmetic in
| `read()`, `flush_decoder` unconditionally overrides `max_length` to
| `-1`, and `_flush_decoder()` passes no limit at all, defaulting to
| unlimited decompression. This allows a malicious HTTP server to
| trigger an out-of-memory (OOM) condition by decompressing large
| payloads into memory, leading to a denial of service (DoS). The
| vulnerability affects urllib3 2.6.3 and Brotli 1.2.0 and impacts
| applications and libraries using `requests` or `urllib3` to stream
| content from untrusted sources.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-9375
https://www.cve.org/CVERecord?id=CVE-2026-9375
[1] https://github.com/urllib3/urllib3/commit/2bdcc44d1e163fb5cc48a8662425e35e15adfe6a

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore

Hello,

Bug #1140427 in python-urllib3 reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/python-team/packages/python-urllib3/-/commit/28273b3a4367c401d50c6e3ffbcde0f71c4a2ff6
------------------------------------------------------------------------
Update upstream source from tag 'upstream/2.7.0'

Update to upstream version '2.7.0'
with Debian dir 0618c7191d12a9f881f0025ef9ef2f7e2410879f

Closes: #1136654, #1140427
------------------------------------------------------------------------

(this message was generated automatically)
-- 
Greetings

https://bugs.debian.org/1140427

We believe that the bug you reported is fixed in the latest version of
python-urllib3, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1140427@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Colin Watson <cjwatson@debian.org> (supplier of updated python-urllib3 package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Sun, 28 Jun 2026 17:48:21 +0100
Source: python-urllib3
Architecture: source
Version: 2.7.0-1
Distribution: unstable
Urgency: medium
Maintainer: Debian Python Team <team+python@tracker.debian.org>
Changed-By: Colin Watson <cjwatson@debian.org>
Closes: 1136654 1140427 1140932
Changes:
 python-urllib3 (2.7.0-1) unstable; urgency=medium
 .
   * Team upload.
   * New upstream release:
     - CVE-2026-44432, CVE-2026-9375: Decompression-bomb safeguards bypassed
       in parts of the streaming API (closes: #1136654, #1140427).
     - GHSA-qccp-gfcp-xxvc: Sensitive headers forwarded across origins in
       proxied low-level redirects.
   * Don't parameterize tests using non-Collection iterables (closes:
     #1140932).
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