---
id: CVE-2026-90231
title: |-
  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 …
summary: |-
  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 …
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc <
    7d1099b86356df81c379159bfb8a598aaf83ce81
  - >-
    Linux >= 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc <
    7da0bdf0610f6d35bbb061536a47fc41646306f0
  - >-
    Linux >= 2d9da9b188b8cd3b579d7ef5ba5d334be9dd38fc <
    08c2f7c8d4b1434cfae006f3daf4d1bce330b57b
  - Linux 6.7
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:48.137'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90231'
references:
  - url: 'https://git.kernel.org/stable/c/08c2f7c8d4b1434cfae006f3daf4d1bce330b57b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7d1099b86356df81c379159bfb8a598aaf83ce81'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7da0bdf0610f6d35bbb061536a47fc41646306f0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00158
epssPercentile: 0.0537
ingestedAt: '2026-09-17T16:21:47.852Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.