CVE-2026-80959 dm-pcache: bound the persisted tail-position offset
A local attacker with CAP_SYS_ADMIN can read past segment boundaries in the Linux kernel dm-pcache driver by manipulating persisted offsets.
- 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-2026-80959?
CVE-2026-80959 is a high-severity path traversal 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: bound the persisted tail-position offset
cache_pos_decode() takes the persisted key_tail and dirty_tail seg_off from the cache device and addresses within the segment with it. A seg_off at or past the segment data_size, controllable by whoever supplies the device (CAP_SYS_ADMIN), reads past the segment data.
Reject a decoded seg_off that is not below the segment data_size.
Which versions are affected by CVE-2026-80959?
How do I fix CVE-2026-80959?
Apply the vendor's patch.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-80959 being exploited?
There is no known exploitation of CVE-2026-80959 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80959, DEBIAN-CVE-2026-80959, GHSA-9gr7-7h3r-cj7p, UBUNTU-CVE-2026-80959.