CVE-2026-89574 dm array: validate array block headers on read
A missing validation in the Linux kernel dm array driver allows out-of-bounds reads, potentially causing crashes or code execution.
- 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-2026-89574?
CVE-2026-89574 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: validate array block headers on read
array_block_check() validates blocknr and csum and nothing else, while node_check(), next to it, has bounded the structural fields since both were written. dm_array_cursor_next() takes its loop bound from the on-disk nr_entries and element_at() is unguarded pointer arithmetic, so a count larger than the block holds keeps the cursor in one block while the index grows past it and the read walks off the dm-bufio buffer -- dm_cache_load_mappings() drives it once per cache block at activation.
Check the header against itself: reject a zero value_size, require max_entries to equal calc_max_entries() for that value_size and block size, and require nr_entries to fit. Equality rather than an upper bound, since a count below the real capacity trips BUG_ON() in fill_ablock() and trim_ablock(). Metadata dm-array writes satisfies all three.
Which versions are affected by CVE-2026-89574?
How do I fix CVE-2026-89574?
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-2026-89574 being exploited?
There is no known exploitation of CVE-2026-89574 in the wild and no public exploit code.
Sources
Also known as AZL-100133, BELL-CVE-2026-89574, DEBIAN-CVE-2026-89574, GHSA-ccr8-4v7h-gw2w, UBUNTU-CVE-2026-89574.