CVE-2026-80961 dm-pcache: validate kset key_num and intra-segment bounds
A local attacker with CAP_SYS_ADMIN can trigger an out-of-bounds read in the Linux kernel dm-pcache driver, leaking adjacent persistent memory to user space.
- 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-2026-80961?
CVE-2026-80961 is a high-severity 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: validate kset key_num and intra-segment bounds
Two more fields decoded from the cache device go unbounded. The kset key_num drives cache_kset_crc() and the replay loop in cache_replay(), the writeback worker and the GC worker, but only the magic and a fixed-seed CRC are checked first, so a non-last kset whose key_num exceeds the PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare. A key's intra-segment offset and length in cache_key_decode() are taken verbatim, so a key running past its segment is replayed into the cache tree and the data CRC check and every later read hit then copy adjacent persistent memory into the caller's bio -- an out-of-bounds read that leaks to user space. Both fields are controlled by whoever supplies the cache device (CAP_SYS_ADMIN); the CRC seed is public.
Add kset_onmedia_valid() to bound key_num before any kset read, and reject a key whose offset plus length, computed in 64 bits, exceeds the segment data_size. Valid metadata is unaffected.
Which versions are affected by CVE-2026-80961?
How do I fix CVE-2026-80961?
Apply the vendor's patch.
Is CVE-2026-80961 being exploited?
There is no known exploitation of CVE-2026-80961 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80961, DEBIAN-CVE-2026-80961, GHSA-7hfq-329h-84pc, UBUNTU-CVE-2026-80961.