USN-7851-2: runC regression

USN-7851-2: runC regression

Publication date: 24 November 2025
Overview: USN-7851-1 introduced a regression in runC

Packages
runc-app - Open Container Project
runc-stable - Open Container Project

Details
USN-7851-1 fixed vulnerabilities in runC. The introduction of a new
upstream release has caused regressions in runc-app and runc-stable.
This update fixes the problem.

Original advisory details:
Lei Wang and Li Fubang discovered that runC incorrectly handled masked
paths. An attacker could possibly replace a container’s /dev/null
with a symlink to some other procfs file and possibly escape a container.
(CVE-2025-31133)

Lei Wang and Li Fubang discovered that runC incorrectly handled the
/dev/console bind-mounts. An attacker could potentially exploit this issue
to build-mount a symlink and escape a container. (CVE-2025-52565)

Li Fubang and Tõnis Tiigi discovered that the fix for CVE-2019-16884 was
incomplete. An attacker could possibly use this issue to cause a denial of
service or escape the container. (CVE-2025-52881)

Update instructions
In general, a standard system update will make all the necessary changes.
The problem can be corrected by updating your system to the following package versions:

25.10 questing

• runc – 1.3.3-0ubuntu1~25.10.3
• runc-stable – 1.3.3-0ubuntu1~25.10.3

25.04 plucky

• runc – 1.3.3-0ubuntu1~25.04.3

24.04 LTS noble

• runc – 1.3.3-0ubuntu1~24.04.3

22.04 LTS jammy

• runc – 1.3.3-0ubuntu1~22.04.3