Published Sep 17, 2026Sources checked Oct 21, 2026
8.4HIGHCVSS out of 10
What this means
Review the available evidence
CVE-2026-90231 and is rated High severity with a CVSS score of 8.4. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
CISA KEVNot listedBased on the latest collected catalog
EPSS0.2%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-90231?
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.