Debian alert DLA-4455-1 (python3.9)

From:
             
 
Andrej Shadura <andrewsh@debian.org>
To:
             
 
debian-lts-announce@lists.debian.org
Subject:
             
 
[SECURITY] [DLA 4455-1] python3.9 security update
Date:
             
 
Sun, 25 Jan 2026 23:41:57 +0100
Message-ID:
             
 
<20260125224200.2230976-1-andrewsh@debian.org>
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Debian LTS Advisory DLA-4455-1                debian-lts@lists.debian.org
https://www.debian.org/lts/security/                       Andrej Shadura
January 25, 2026                              https://wiki.debian.org/LTS
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Package        : python3.9
Version        : 3.9.2-1+deb11u5
CVE ID         : CVE-2025-11468 CVE-2025-12084 CVE-2025-15282 CVE-2025-15366 
                 CVE-2025-15367 CVE-2026-0672 CVE-2026-0865 CVE-2026-1299

This upload fixes a regression introduced in 3.9.2-1+deb11u4 (DLA 4445-1),
and also fixes multiple security issues in cPython 3.9.

CVE-2025-12084

    When building nested elements using xml.dom.minidom methods such
    as appendChild() that have a dependency on _clear_id_cache() the
    algorithm was quadratic. Availability could be impacted when building
    excessively nested documents.

    The fix for this CVE in the previous upload resulted in a regression
    in software relying on ownerDocument attribute being always present
    in Element instances. This regression has now been fixed.

CVE-2026-0672, CVE-2026-0865, CVE-2025-15282, CVE-2025-15366, CVE-2025-15367

    These are all similar vulnerabilities in the following modules:
    http.cookies, wsgiref.headers, imaplib, poplib, urllib. In each of
    these control characters were handled incorrectly, allowing injection
    of additional cookiers, headers or commands. Control characters are
    now rejected in these contexts.

CVE-2025-11468

    An issue similar to the above. Comments consisting of a very long
    sequence of non-foldable characters could trigger a forced line wrap
    that omitted the required leading space on the continuation line,
    causing the remainder of the comment to be interpreted as a new
    header field.

CVE-2026-1299

    Another header injection issue: email module allowed header injection in the
    BytesGenerator class. BytesGenerator will now refuse to serialize headers
    that are unsafely folded or delimited.

For Debian 11 bullseye, these problems have been fixed in version
3.9.2-1+deb11u5.

We recommend that you upgrade your python3.9 packages.

For the detailed security status of python3.9 please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/python3.9

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
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