CVE-2026-89573 dm array: reject an array block whose value size is not the caller's
A flaw in the Linux kernel dm-cache allows attackers to cause memory corruption via crafted metadata, potentially leading to code execution or privilege escalation.
- 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-2026-89573?
CVE-2026-89573 is a high-severity memory corruption vulnerability in Linux, published on 11 Sep 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:
dm array: reject an array block whose value size is not the caller's
array_block_check() can only compare the header against itself, so a block with value_size 4 and max_entries 1018 is internally consistent and passes. dm-cache keeps two arrays -- mappings at 8 bytes and hints at 4 -- and the roots for both live in the superblock. Point the mappings root at a hint block and __load_mappings() walks it through an info whose value size is 8, so element_at() strides 8 bytes over 4-byte entries and reaches offset 8160 of a 4096-byte block.
get_ablock() and __shadow_ablock() are the two places that hold the block and the caller at once. Reject there when the two value sizes disagree. Arrays only ever read their own blocks, so this fires on crafted metadata only.
Which versions are affected by CVE-2026-89573?
How do I fix CVE-2026-89573?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89573 being exploited?
There is no known exploitation of CVE-2026-89573 in the wild and no public exploit code.
Sources
Also known as AZL-100521, BELL-CVE-2026-89573, DEBIAN-CVE-2026-89573, GHSA-pg3h-8qxx-35hj, UBUNTU-CVE-2026-89573.