Home / mailings [USN-8018-2] Python regression
Posted on 09 March 2026
Ubuntu Security==========================================================================Ubuntu Security Notice USN-8018-2
March 09, 2026
python3.4, python3.5, python3.6, python3.7, python3.8, python3.9,
python3.10, python3.11, python3.12, python3.13, python3.14 regression
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS
Summary:
USN-8018-1 introduced a regression in Python
Software Description:
- python3.13: An interactive high-level object-oriented language
- python3.14: An interactive high-level object-oriented language
- python3.12: An interactive high-level object-oriented language
- python3.10: An interactive high-level object-oriented language
- python3.11: An interactive high-level object-oriented language
- python3.8: An interactive high-level object-oriented language
- python3.9: An interactive high-level object-oriented language
- python3.6: An interactive high-level object-oriented language
- python3.7: An interactive high-level object-oriented language
- python3.5: An interactive high-level object-oriented language
- python3.4: An interactive high-level object-oriented language
Details:
USN-8018-1 fixed vulnerabilities in python3. That update introduced
regressions. The patches for CVE-2025-15366 and CVE-2025-15367 caused
behavior regressions in IMAP and POP3 handling, which upstream chose to
avoid by not backporting them. Additionally, the patch for CVE-2026-0865
incorrectly rejected horizontal tabs in wsgiref headers. This update fixes
these problems.
We apologize for the inconvenience.
Original advisory details:
Denis Ledoux discovered that Python incorrectly parsed email message
headers. An attacker could possibly use this issue to inject arbitrary
headers into email messages. This issue only affected python3.6,
python3.7, python3.8, python3.9, python3.10, python3.11, python3.12,
python3.13, and python3.14 packages. (CVE-2025-11468)
Jacob Walls, Shai Berger, and Natalia Bidart discovered that Python
inefficiently parsed XML input with quadratic complexity. An attacker
could possibly use this issue to cause a denial of service.
(CVE-2025-12084)
It was discovered that Python incorrectly parsed malicious plist files. An
attacker could possibly use this issue to cause Python to use excessive
resources, leading to a denial of service. This issue only affected
python3.5, python3.6, python3.7, python3.8, python3.9, python3.10,
python3.11, python3.12, python3.13, and python3.14 packages.
(CVE-2025-13837)
Omar Hasan discovered that Python incorrectly parsed URL mediatypes. An
attacker could possibly use this issue to inject arbitrary HTTP headers.
(CVE-2025-15282)
Omar Hasan discovered that Python incorrectly parsed malicious IMAP
inputs. An attacker could possibly use this issue to inject arbitrary
IMAP commands. (CVE-2025-15366)
Omar Hasan discovered that Python incorrectly parsed malicious POP3
inputs. An attacker could possibly use this issue to inject arbitrary
POP3 commands. (CVE-2025-15367)
Omar Hasan discovered that Python incorrectly parsed malicious HTTP cookie
headers. An attacker could possibly use this issue to inject arbitrary
HTTP headers. (CVE-2026-0672)
Omar Hasan discovered that Python incorrectly parsed malicious HTTP header
names and values. An attacker could possibly use this issue to inject
arbitrary HTTP headers. (CVE-2026-0865)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 25.10
libpython3.13 3.13.7-1ubuntu0.4
libpython3.14 3.14.0-1ubuntu0.3
python3.13 3.13.7-1ubuntu0.4
python3.14 3.14.0-1ubuntu0.3
Ubuntu 24.04 LTS
libpython3.12t64 3.12.3-1ubuntu0.12
python3.12 3.12.3-1ubuntu0.12
Ubuntu 22.04 LTS
libpython3.10 3.10.12-1~22.04.15
libpython3.11 3.11.0~rc1-1~22.04.1~esm9
Available with Ubuntu Pro
python3.10 3.10.12-1~22.04.15
python3.11 3.11.0~rc1-1~22.04.1~esm9
Available with Ubuntu Pro
Ubuntu 20.04 LTS
libpython3.8 3.8.10-0ubuntu1~20.04.18+esm6
Available with Ubuntu Pro
libpython3.9 3.9.5-3ubuntu0~20.04.1+esm10
Available with Ubuntu Pro
python3.8 3.8.10-0ubuntu1~20.04.18+esm6
Available with Ubuntu Pro
python3.9 3.9.5-3ubuntu0~20.04.1+esm10
Available with Ubuntu Pro
Ubuntu 18.04 LTS
libpython3.6 3.6.9-1~18.04ubuntu1.13+esm9
Available with Ubuntu Pro
libpython3.7 3.7.5-2ubuntu1~18.04.2+esm10
Available with Ubuntu Pro
libpython3.8 3.8.0-3ubuntu1~18.04.2+esm10
Available with Ubuntu Pro
python3.6 3.6.9-1~18.04ubuntu1.13+esm9
Available with Ubuntu Pro
python3.7 3.7.5-2ubuntu1~18.04.2+esm10
Available with Ubuntu Pro
python3.8 3.8.0-3ubuntu1~18.04.2+esm10
Available with Ubuntu Pro
Ubuntu 16.04 LTS
libpython3.5 3.5.2-2ubuntu0~16.04.13+esm22
Available with Ubuntu Pro
python3.5 3.5.2-2ubuntu0~16.04.13+esm22
Available with Ubuntu Pro
Ubuntu 14.04 LTS
libpython3.4 3.4.3-1ubuntu1~14.04.7+esm20
Available with Ubuntu Pro
libpython3.5 3.5.2-2ubuntu0~16.04.4~14.04.1+esm10
Available with Ubuntu Pro
python3.4 3.4.3-1ubuntu1~14.04.7+esm20
Available with Ubuntu Pro
python3.5 3.5.2-2ubuntu0~16.04.4~14.04.1+esm10
Available with Ubuntu Pro
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-8018-2
https://ubuntu.com/security/notices/USN-8018-1
CVE-2025-15366, CVE-2025-15367, CVE-2026-0865, https://bugs.launchpad.net/bugs/2143706
Package Information:
https://launchpad.net/ubuntu/+source/python3.13/3.13.7-1ubuntu0.4
https://launchpad.net/ubuntu/+source/python3.14/3.14.0-1ubuntu0.3
https://launchpad.net/ubuntu/+source/python3.12/3.12.3-1ubuntu0.12
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