CVE-2026-23223 xfs: fix UAF in xchk_btree_check_block_owner
A use-after-free flaw in the Linux kernel XFS filesystem allows attackers to potentially execute arbitrary code or escalate privileges.
- 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-2026-23223?
CVE-2026-23223 is a high-severity use after free vulnerability in Linux kernel, published on 18 Feb 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:
xfs: fix UAF in xchk_btree_check_block_owner
We cannot dereference bs->cur when trying to determine if bs->cur aliases bs->sc->sa.{bno,rmap}_cur after the latter has been freed. Fix this by sampling before type before any freeing could happen. The correct temporal ordering was broken when we removed xfs_btnum_t.
Weakness: CWE-416
Which versions are affected by CVE-2026-23223?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23223?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-23223 being exploited?
There is no known exploitation of CVE-2026-23223 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-23223, DEBIAN-CVE-2026-23223, GHSA-h437-rr98-fx56, ROOT-OS-DEBIAN-11-CVE-2026-23223, ROOT-OS-DEBIAN-12-CVE-2026-23223, UBUNTU-CVE-2026-23223.