USN-7851-1: runC vulnerabilities

Publication date

4 November 2025

Overview

Several security issues were fixed in runC.


Packages

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)

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

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
25.10 questing runc –  1.3.3-0ubuntu1~25.10.2
runc-stable –  1.3.3-0ubuntu1~25.10.2
25.04 plucky runc –  1.3.3-0ubuntu1~25.04.2
24.04 LTS noble runc –  1.3.3-0ubuntu1~24.04.2
22.04 LTS jammy runc –  1.3.3-0ubuntu1~22.04.2

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