CVE-2023-25809mediumCWE-281

CVE-2023-25809: medium-severity vulnerability in opencontainers runc

rootless: `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc

Published · Updated

Follow this CVE+ Monitor runc+ Monitor runc

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5epss 0.3%
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`.
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L
Affected products
opencontainers · runc
Related CVEs — opencontainers runc

In the same product, most dangerous first.

CVE-2024-21626HIGHrunc container breakout through process.cwd trickery and leaked fdsEPSS 18.9%CVE-2021-43784MEDIUMOverflow in netlink bytemsg length field allows attacker to override netlink-based container configurationEPSS 1.8%CVE-2025-31133HIGHrunc container escape via "masked path" abuse due to mount race conditionsEPSS 1.2%CVE-2025-52565HIGHcontainer escape due to /dev/console mount and related racesEPSS 0.8%CVE-2025-52881HIGHrunc: LSM labels can be bypassed with malicious config using dummy procfs filesEPSS 0.8%CVE-2022-29162MEDIUMIncorrect Default Permissions in runcEPSS 0.4%