runc container escape and denial of service due to arbitrary write gadgets and procfs write redirects

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.3 · 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 · score source

EPSS

• CVE-2025-52881: 0.80% estimated exploitation activity in the next 30 days; percentile 56.67 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact

This attack is primarily a more sophisticated version of CVE-2019-19921, which was a flaw which allowed an attacker to trick runc into writing the LSM process labels for a container process into a dummy tmpfs file and thus not apply the correct LSM labels to the container process. The mitigation runc applied for CVE-2019-19921 was fairly limited and effectively only caused runc to verify that when runc writes LSM labels that those labels are actual procfs files. Rather than using a fake tmpfs file for /proc/self/attr/<label, an attacker could instead (through various means) make /proc/self/attr/<label reference a real procfs file, but one that would still be a no-op (such as /proc/self/sched). This would have the same effect but would clear the "is a procfs file" check. Runc is aware that this kind of attack would be possible (even going so far as to discuss this publicly as "future work" at conferences), and runc is working on a far more comprehensive mitigation of this…

Published by the source

5 Nov 2025, 18:40 UTC

Last modified by the source

7 Nov 2025, 12:31 UTC

Source last checked

26 Oct 2026, 15:13 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cgrx-mc8f-2prm

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# Patch Next advisory brief: CVE-2025-52881

Advisory: runc container escape and denial of service due to arbitrary write gadgets and procfs write redirects
IDs: CVE-2025-52881, GHSA-cgrx-mc8f-2prm
Record: https://patchnext.com/advisories/cve-2025-52881 (revision 1, source checked 26 Oct 2026, 15:13 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/opencontainers/runc 1.4.0-rc.3, 1.3.3, 1.2.8; github.com/opencontainers/selinux 1.13.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/opencontainers/runc: affected <= 1.2.7; >= 1.3.0-rc.1, <= 1.3.2; >= 1.4.0-rc.1, <= 1.4.0-rc.2; fixed in 1.2.8, 1.3.3, 1.4.0-rc.3
- Go github.com/opencontainers/selinux: affected <= 1.12.0; fixed in 1.13.0

## Suggested inspection (read-only)
- Go github.com/opencontainers/runc: check the installed version with your package manager.
- Go github.com/opencontainers/selinux: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/opencontainers/runc, github.com/opencontainers/selinux.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cgrx-mc8f-2prm (GitHub-reviewed advisory GHSA-cgrx-mc8f-2prm lists affected ranges: Go github.com/opencontainers/runc >=0 =1.3.0-rc.1 =1.4.0-rc.1 =0 <=1.12.0)

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