apparmor: fix unconfined user namespace restriction forced stack
CVE-2026-90231 · published 17 Sept 2026
How serious is it
- Severity: high, CVSS score 8.4 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-90231?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Linux Linux: 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc to < fdd341654471cae4fbd9635d32b848cd0c8bc437, 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc to < 7d1099b86356df81c379159bfb8a598aaf83ce81, 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc to < 7da0bdf0610f6d35bbb061536a47fc41646306f0, 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc to < 08c2f7c8d4b1434cfae006f3daf4d1bce330b57b
- Linux Linux: 6.7
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix unconfined user namespace restriction forced stack
If a task is already confined by a stack the unprivileged transition
restriction on unconfined is not correctly, applied. This results in
an escape if two transitions through an unconfined profile can be
executed.
Fix this by pushing the check into the per profile label build. The
check will always be done against unconfined and result in a stack of
just the unconfined component when necessary.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/fdd341654471cae4fbd9635d32b848cd0c8bc437
- git.kernel.org/stable/c/7d1099b86356df81c379159bfb8a598aaf83ce81
- git.kernel.org/stable/c/7da0bdf0610f6d35bbb061536a47fc41646306f0
- git.kernel.org/stable/c/08c2f7c8d4b1434cfae006f3daf4d1bce330b57b
Merged from CVE List. Last updated 26 Oct 2026. All vulnerabilities · RSS · JSON