CVE-2026-90231: apparmor: fix unconfined user namespace restriction forced stack
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.
Affected Software
Event History
Frequently Asked Questions
What conditions are required for exploitation?
The task must already be confined by an AppArmor stack, and an attacker must be able to execute two transitions through an unconfined profile. Under those conditions, the unprivileged transition restriction may not be applied correctly.
What is the potential impact?
The issue can result in an escape from the existing confinement when the required transitions through an unconfined profile are performed.
Which systems should be investigated for exposure?
Investigate Linux kernel systems using AppArmor where tasks can operate under stacked confinement and perform transitions through unconfined profiles. The provided information does not identify specific kernel versions or default configurations.