CVE-2026-80956 dm-pcache: only hand out initialized cache segments
A crafted disk image can cause a null pointer dereference in the Linux kernel dm-pcache module, leading to a system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80956?
CVE-2026-80956 is a 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: only hand out initialized cache segments
get_cache_segment() scans the segment map up to cache->n_segs, the physical device segment count, but cache_segs_init() only initializes the first cache_info->n_segs segments. A crafted image with cache_info->n_segs smaller than the device count leaves the remaining pcache_cache_segment structs zeroed (segment.data == NULL), and the allocator can hand one to cache_kset_close(), which writes through the returned segment's data pointer with no NULL check.
Bound the allocator's search to cache_info->n_segs so only initialized segments are ever returned. A conforming cache sets n_segs equal to the device segment count, so this rejects nothing legitimate.
Which versions are affected by CVE-2026-80956?
How do I fix CVE-2026-80956?
Apply the vendor's patch.
Is CVE-2026-80956 being exploited?
There is no known exploitation of CVE-2026-80956 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80956, DEBIAN-CVE-2026-80956, GHSA-2r45-hwhh-3hc3, UBUNTU-CVE-2026-80956.