CVE-2025-31133: Linuxfoundation Runc

High severity, CVSS 7.8. EPSS: 0.8% chance of exploitation in the next 30 days.

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

• Linuxfoundation Runc: before 1.2.8 (fixed in 1.2.8); from 1.3.0, before 1.3.3 (fixed in 1.3.3); version 1.4.0 only

Published 2025-11-06. Last modified 2026-10-07.