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

Advisory record · `GHSA-m8cg-xc2p-r3fc`

- **Identifiers:** `GHSA-m8cg-xc2p-r3fc` · `CVE-2023-25809` · `GO-2023-1682`
- **State:** Confirmed
- **Severity:** CVSS 5.0 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-281](https://cwe.mitre.org/data/definitions/281.html)
- **Tags:** [CWE-281](https://agentprime.io/advisories/tag/cwe-281.md)
- **Published:** 30 Mar 2023
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Mar 2023, 20:17 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/opencontainers/runc` (Go): affected `<1.1.5`; fixed in `1.1.5`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> runc versions before 1.1.5 leave /sys/fs/cgroup writable in some rootless setups where the cgroup namespace is not unshared. A container started this way can write to the user-owned cgroup hierarchy on the host, though other users' hierarchies are not affected. Upgrade to runc 1.1.5, or until then run containers with a private cgroup namespace.

Written 5 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.0 Medium, CVSS 3.1: `CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0032, the 25th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:43 UTC: First seen by agentprime
- 31 Oct 2026, 14:43 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-m8cg-xc2p-r3fc)

## Sources

- [GitHub Advisory Database: GHSA-m8cg-xc2p-r3fc](https://github.com/advisories/GHSA-m8cg-xc2p-r3fc)
- [OSV: GHSA-m8cg-xc2p-r3fc](https://osv.dev/vulnerability/GHSA-m8cg-xc2p-r3fc)
- <https://github.com/opencontainers/runc/security/advisories/GHSA-m8cg-xc2p-r3fc>
- <https://nvd.nist.gov/vuln/detail/CVE-2023-25809>
- <https://github.com/opencontainers/runc/commit/0d62b950e60f6980b54fe3bafd9a9c608dc1df17>
- <https://github.com/opencontainers/runc>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-m8cg-xc2p-r3fc>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-m8cg-xc2p-r3fc/>. Everything for agents: <https://agentprime.io/llms.txt>.