What’s Vulnerable › Vulnerabilities

CVE-2025-31133: runc container escape via "masked path" abuse due to mount race conditions

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-11-06 · updated 2026-10-07
• Weakness: CWE-61

Description

runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.2.7 and below, 1.3.0-rc.1 through 1.3.1, 1.4.0-rc.1 and 1.4.0-rc.2 files, runc would not perform sufficient verification that the source of the bind-mount (i.e., the container's /dev/null) was actually a real /dev/null inode when using the container's /dev/null to mask. This exposes two methods of attack: an arbitrary mount gadget, leading to host information disclosure, host denial of service, container escape, or a bypassing of maskedPaths. This issue is fixed in versions 1.2.8, 1.3.3 and 1.4.0-rc.3.

Affected products

• opencontainers runc: before 1.2.8; from 1.3.0 before 1.3.3; 1.4.0-rc1, 1.4.0-rc2 — fixed in 1.2.8, 1.3.3

How to fix

Upgrade to a fixed version: opencontainers runc 1.2.8, 1.3.3. Check the vendor advisory for mitigations.

References

• https://github.com/opencontainers/runc/commit/1a30a8f3d921acbbb6a4bb7e99da2c05f8d48522
• https://github.com/opencontainers/runc/commit/5d7b2424072449872d1cd0c937f2ca25f418eb66
• https://github.com/opencontainers/runc/commit/8476df83b534a2522b878c0507b3491def48db9f
• https://github.com/opencontainers/runc/commit/db19bbed5348847da433faa9d69e9f90192bfa64
• https://github.com/opencontainers/runc/security/advisories/GHSA-9493-h29p-rfm2

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