Ubuntu 25.10 runC Important Security Fixes Denial of Service USN-7851-1

ubuntu

November 5, 2025

Several security issues were fixed in runC.

Summary

Several security issues were fixed in runC.

Software Description:

- runc-app: Open Container Project

- runc-stable: Open Container Project

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)

Topics Covered

security advisory denial of service Ubuntu important runc container escape

Update Instructions

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

Ubuntu 25.10
  runc                            1.3.3-0ubuntu1~25.10.2
  runc-stable                     1.3.3-0ubuntu1~25.10.2

Ubuntu 25.04
  runc                            1.3.3-0ubuntu1~25.04.2

Ubuntu 24.04 LTS
  runc                            1.3.3-0ubuntu1~24.04.2

Ubuntu 22.04 LTS
  runc                            1.3.3-0ubuntu1~22.04.2

This update uses a new upstream release, which includes additional bug
fixes. In general, a standard system update will make all the necessary
changes.