GHSA-m8cg-xc2p-r3fc
LOWrootless: `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/opencontainers/runcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
It was found that rootless runc makes /sys/fs/cgroup writable in following conditons:
- when runc is executed inside the user namespace, and the
config.jsondoes not specify the cgroup namespace to be unshared (e.g..,(docker|podman|nerdctl) run --cgroupns=host, with Rootless Docker/Podman/nerdctl) - or, when runc is executed outside the user namespace, and
/sysis mounted withrbind, 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.
Patches
v1.1.5 (planned)
Workarounds
- Condition 1: Unshare the cgroup namespace (
(docker|podman|nerdctl) run --cgroupns=private). This is the default behavior of Docker/Podman/nerdctl on cgroup v2 hosts. - Condition 2 (very rare): add
/sys/fs/cgrouptomaskedPaths
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/opencontainers/runc | all versions | 1.1.5 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/opencontainers/runc. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/opencontainers/runc to 1.1.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m8cg-xc2p-r3fc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-m8cg-xc2p-r3fc is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-m8cg-xc2p-r3fc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-m8cg-xc2p-r3fc in your dependencies?
O3 detects GHSA-m8cg-xc2p-r3fc across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.