CVE-2026-23404 apparmor: replace recursive profile removal with iterative approach
A local attacker can crash the Linux kernel by creating deeply nested AppArmor profiles, causing stack exhaustion during profile removal.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23404?
CVE-2026-23404 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
apparmor: replace recursive profile removal with iterative approach
The profile removal code uses recursion when removing nested profiles, which can lead to kernel stack exhaustion and system crashes.
Reproducer: $ pf='a'; for ((i=0; i<1024; i++)); do echo -e "profile $pf { \n }" | apparmor_parser -K -a; pf="$pf//x"; done $ echo -n a > /sys/kernel/security/apparmor/.remove
Replace the recursive __aa_profile_list_release() approach with an iterative approach in __remove_profile(). The function repeatedly finds and removes leaf profiles until the entire subtree is removed, maintaining the same removal semantic without recursion.
Which versions are affected by CVE-2026-23404?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23404?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-23404 being exploited?
There is no known exploitation of CVE-2026-23404 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-82016, BELL-CVE-2026-23404, DEBIAN-CVE-2026-23404, GHSA-x9jq-3w57-m487, UBUNTU-CVE-2026-23404.