Ubuntu: Python Important Denial Of Service Issue USN-7951-1 CVE-2025-13836

ubuntu

January 12, 2026

Python could be made to crash if it received specially crafted network traffic.

Summary

Python could be made to crash if it received specially crafted network

traffic.

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

Details:

It was discovered that Python's http.client did not properly handle the

Content-Length header in HTTP responses. A malicious server could exploit

this to cause Python to allocate excessive memory, leading to a denial of

service.

Topics Covered

security advisory denial of service Ubuntu important network traffic python

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 25.10
  libpython3.13                   3.13.7-1ubuntu0.2
  libpython3.14                   3.14.0-1ubuntu0.1
  python3.13                      3.13.7-1ubuntu0.2
  python3.14                      3.14.0-1ubuntu0.1

Ubuntu 25.04
  libpython3.13                   3.13.3-1ubuntu0.5
  python3.13                      3.13.3-1ubuntu0.5

Ubuntu 24.04 LTS
  libpython3.12t64                3.12.3-1ubuntu0.10
  python3.12                      3.12.3-1ubuntu0.10

Ubuntu 22.04 LTS
  libpython3.10                   3.10.12-1~22.04.13
  libpython3.11                   3.11.0~rc1-1~22.04.1~esm7
                                  Available with Ubuntu Pro
  python3.10                      3.10.12-1~22.04.13
  python3.11                      3.11.0~rc1-1~22.04.1~esm7
                                  Available with Ubuntu Pro

Ubuntu 20.04 LTS
  libpython3.8                    3.8.10-0ubuntu1~20.04.18+esm4
                                  Available with Ubuntu Pro
  libpython3.9                    3.9.5-3ubuntu0~20.04.1+esm8
                                  Available with Ubuntu Pro
  python3.8                       3.8.10-0ubuntu1~20.04.18+esm4
                                  Available with Ubuntu Pro
  python3.9                       3.9.5-3ubuntu0~20.04.1+esm8
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libpython3.8                    3.8.0-3ubuntu1~18.04.2+esm8
                                  Available with Ubuntu Pro
  python3.8                       3.8.0-3ubuntu1~18.04.2+esm8
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.