CVE-2026-80955 dm-pcache: fix use-after-free and invalid seg operations in kset_replay()
A use-after-free vulnerability in the Linux kernel's dm-pcache module allows attackers to potentially execute code or cause a system crash.
- 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-2026-80955?
CVE-2026-80955 is a high-severity use after free 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-pcache: fix use-after-free and invalid seg operations in kset_replay()
In kset_replay, when key->seg_gen is stale (key->seg_gen < key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then key->cache_pos.cache_seg is accessed as the argument to cache_seg_get(). This is a use-after-free on the freed key memory. Although mempool recycled memory is not immediately reclaimed or overwritten in practice, this is still a potential UAF bug.
Additionally, for expired invalid keys, setting the cache->seg_map bit and calling cache_seg_get() is unreasonable since the corresponding segment data is no longer valid.
Fix both issues by moving cache_seg_get() and __set_bit() after the gen check, so they only execute for valid keys, and using continue to skip invalid keys.
Which versions are affected by CVE-2026-80955?
How do I fix CVE-2026-80955?
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-2026-80955 being exploited?
There is no known exploitation of CVE-2026-80955 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80955, DEBIAN-CVE-2026-80955, GHSA-vjx8-9mvv-9939, UBUNTU-CVE-2026-80955.