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MEDIUM severity

CVE-2023-25809 — runc

MEDIUMFix: opencontainers/runc@0d62b95

CVE-2023-25809 is a medium-severity (CVSS 5) CWE-281 vulnerability in github.com/opencontainers/runc. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for github.com/opencontainers/runc — see the affected versions and patch details below.

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

Also known asGHSA-m8cg-xc2p-r3fcGO-2023-1682
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-25809.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk
0.00%0.28%0.55%0.83%0.0%0.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/opencontainers/runc

Real-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

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 Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/opencontainers/runcall versions1.1.5go get github.com/opencontainers/runc@v1.1.5

Affected Products

1 product · 1 configurations
Application
runclinuxfoundation
< 1.1.5
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

runc is a CLI tool for spawning and running containers according to the …

github.comNVDApr 2023

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/opencontainers/runc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. 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 CVE-2023-25809 is resolved across your whole dependency graph.

  3. 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
Workaround published by Red Hat
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/cgroup to maskedPaths
Source: Red Hat security advisory for CVE-2023-25809 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Enterprise Linux 8container-tools:4.0-8090020230828093056.e7857ab1RHSA-2023:6938
Red Hat Enterprise Linux 8container-tools:rhel8-8090020230825121312.e7857ab1RHSA-2023:6939
Red Hat Enterprise Linux 9runc-4:1.1.9-1.el9RHSA-2023:6380
Red Hat OpenShift Container Platform 4.13openshift4/ose-vsphere-csi-driver-syncer-rhel8:v4.13.0-202304190216.p0.g6f4295b.assembly.streamRHSA-2023:1326

Frequently Asked Questions

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
O3 Security · Impact-Aware SCA

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CVE-2023-25809: runc — Fixed in 1.1.5