CVE-2025-52881runc: LSM labels can be bypassed with malicious config using dummy procfs files

Official description

runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.2.7, 1.3.2 and 1.4.0-rc.2, an attacker can trick runc into misdirecting writes to /proc to other procfs files through the use of a racing container with shared mounts (we have also verified this attack is possible to exploit using a standard Dockerfile with docker buildx build as that also permits triggering parallel execution of containers with custom shared mounts configured). This redirect could be through symbolic links in a tmpfs or theoretically other methods such as regular bind-mounts. While similar, the mitigation applied for the related CVE, CVE-2019-19921, was fairly limited and effectively only caused runc to verify that when LSM labels are written they are actually procfs files. This issue is fixed in versions 1.2.8, 1.3.3, and 1.4.0-rc.3.

Affected packages & fixed versions

Affected products (as reported)

References

• https://github.com/opencontainers/runc/security/advisories/GHSA-cgrx-mc8f-2prm x_refsource_CONFIRM
• https://github.com/opencontainers/runc/security/advisories/GHSA-qw9x-cqr3-wc7r x_refsource_MISC
• https://github.com/opencontainers/runc/security/advisories/GHSA-9493-h29p-rfm2 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/ff94f9991bd32076c871ef0ad8bc1b763458e480 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/ff6fe1324663538167eca8b3d3eec61e1bd4fa51 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/ed6b1693b8b3ae7eb0250a7e76fc888cdacf98c1 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/db19bbed5348847da433faa9d69e9f90192bfa64 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/d61fd29d854b416feaaf128bf650325cd2182165 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/d40b3439a9614a86e87b81a94c6811ec6fa2d7d2 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/b3dd1bc562ed9996d1a0f249e056c16624046d28 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/77d217c7c3775d8ca5af89e477e81568ef4572db x_refsource_MISC
• https://github.com/opencontainers/runc/commit/77889b56db939c323d29d1130f28f9aea2edb544 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/6fc191449109ea14bb7d61238f24a33fe08c651f x_refsource_MISC
• https://github.com/opencontainers/runc/commit/4b37cd93f86e72feac866442988b549b5b7bf3e6 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/44a0fcf685db051c80b8c269812bb177f5802c58 x_refsource_MISC
• https://github.com/opencontainers/runc/commit/435cc81be6b79cdec73b4002c0dae549b2f6ae6d x_refsource_MISC
• https://github.com/opencontainers/runc/commit/3f925525b44d247e390e529e772a0dc0c0bc3557 x_refsource_MISC
• https://github.com/opencontainers/runc/blob/v1.4.0-rc.2/RELEASES.md x_refsource_MISC
• http://github.com/opencontainers/runc/commit/a41366e74080fa9f26a2cd3544e2801449697322 x_refsource_MISC
• http://github.com/opencontainers/runc/commit/fdcc9d3cad2f85954a241ccb910a61aaa1ef47f3 x_refsource_MISC