CVE-2023-25809
rootless: `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc
runc is a CLI tool for spawning and running containers according to the OCI specification. In affected versions it was found that rootless runc makes `/sys/fs/cgroup` writable in following conditons: 1. when runc is executed inside the user namespace, and the `config.json` does not specify the cgroup namespace to be unshared (e.g.., `(docker|podman|nerdctl) run --cgroupns=host`, with Rootless Docker/Podman/nerdctl) or 2. when runc is executed outside the user namespace, and `/sys` is mounted with `rbind, ro` (e.g., `runc spec --rootless`; this condition is very rare). A container may gain the write access to user-owned cgroup hierarchy `/sys/fs/cgroup/user.slice/...` on the host . Other users's cgroup hierarchies are not affected. Users are advised to upgrade to version 1.1.5. Users unable to upgrade may unshare the cgroup namespace (`(docker|podman|nerdctl) run --cgroupns=private)`. This is the default behavior of Docker/Podman/nerdctl on cgroup v2 hosts. or add `/sys/fs/cgroup` to `maskedPaths`.
- Affected
- opencontainers · runc
- CVSS v3.1 NVD
- 6.3 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L - CVSS v3.1 GITHUB
- 5.0 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L - CVSS v3.1 GitHub
- 2.5 LOW
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:L - EPSS
- 0.32% chance of exploitation in the next 30 days, 23rd percentile
- Published
- 2023-03-29
- Updated
- 2025-02-12
Proof-of-concept exploits (1)
- southsidesamurai65-prog/container_all_in_one0★ · 2026-08-08
Security advisories
- opencontainers/runc/security/advisories/GHSA-m8cg-xc2p-r3fc
- advisories/GHSA-m8cg-xc2p-r3fc
- opencontainers/runc/commit/0d62b950e60f6980b54fe3bafd9a9c608dc1df17