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8.4

runc may let attackers bypass security label checks

CVE-2025-52881 · published 11 months ago
Summary

The container command-line tool runc (versions 1.2.7, 1.3.2 and 1.4.0-rc.2) can be tricked into writing security label information to the wrong place, letting a malicious container escape its intended restrictions. This can happen when containers share mount points and the attacker uses specially crafted files to redirect writes. Upgrade runc to version 1.2.8, 1.3.3, or 1.4.0-rc.3 to close the gap.

What to do
  • Update github.com opencontainers to version 1.2.8.
  • Update github.com opencontainers to version 1.13.0.
  • Update github.com opencontainers to version 1.3.3.
  • Update github.com opencontainers to version 1.4.0-rc.3.
  • Update bellsoft buildah to version 1.39.5-r0.
  • Update bellsoft podman to version 5.6.2-r1.
  • Update bellsoft podman to version 5.6.2-r13.
  • Update bellsoft runc to version 1.3.6-r0.
  • Update bellsoft buildah to version 1.41.6-r0.
  • Update bellsoft runc to version 1.3.3-r0.
  • Update bellsoft buildah to version 1.42.1-r0.
  • Update bellsoft podman to version 5.7.0-r0.
  • Update debian runc to version 1.3.3+ds1-2.
Affected software
Ecosystem VendorProductAffected versions
go github.com opencontainers <= 1.2.7
>= 1.3.0-rc.1, <= 1.3.2
>= 1.4.0-rc.1, <= 1.4.0-rc.2
Fix: upgrade to 1.2.8
go github.com opencontainers <= 1.12.0
Fix: upgrade to 1.13.0
– linuxfoundation runc < 1.2.8
>= 1.3.0, < 1.3.3
1.4.0
cpe:2.3:a:linuxfoundation:runc:*:*:*:*:*:*:*:*
Alpaquita:23 bellsoft buildah >= 1.28.0-r1, < 1.39.5-r0
Fix: upgrade to 1.39.5-r0
Alpaquita:23 bellsoft podman >= 4.3.1-r0, < 5.6.2-r1
>= 4.3.1-r0, < 5.6.2-r13
Fix: upgrade to 5.6.2-r1
Alpaquita:25 bellsoft podman >= 5.5.0-r0, < 5.6.2-r13
>= 5.5.0-r0, < 5.6.2-r1
Fix: upgrade to 5.6.2-r13
Alpaquita:23 bellsoft runc >= 1.1.4-r3, < 1.3.6-r0
Fix: upgrade to 1.3.6-r0
Alpaquita:25 bellsoft buildah >= 1.40.0-r0, < 1.41.6-r0
Fix: upgrade to 1.41.6-r0
Alpaquita:25 bellsoft runc >= 1.3.0-r1, < 1.3.3-r0
Fix: upgrade to 1.3.3-r0
Alpaquita:stream bellsoft buildah >= 1.31.0-r0, < 1.42.1-r0
Fix: upgrade to 1.42.1-r0
Alpaquita:stream bellsoft podman >= 4.5.1-r1, < 5.7.0-r0
Fix: upgrade to 5.7.0-r0
Alpaquita:stream bellsoft runc >= 1.3.0-r1, < 1.3.3-r0
Fix: upgrade to 1.3.3-r0
Debian:12 debian runc All versions
Debian:14 debian runc < 1.3.3+ds1-2
Fix: upgrade to 1.3.3+ds1-2
Original advisory text
runc: LSM labels can be bypassed with malicious config using dummy procfs files
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.
References
Fix within
Internet-facing 14 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker full control
Severity
8.4 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-61UNIX Symbolic Link (Symlink) Following
CWE-363Race Condition Enabling Link Following
Timeline
Published6 Nov 2025
Updated4 Nov 2026
First seen6 Mar 2026
Sources
BELL-CVE-2025-52881 · OSV
GHSA-cgrx-mc8f-2prm · GHSA
CVE-2025-52881 · NVD
CVE-2025-52881 · OSV
DEBIAN-CVE-2025-52881 · OSV
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