CVE-2026-98868 dm-pcache: reject a kset that overruns its segment
A local attacker can trigger a kernel crash in dm-pcache by forging a kset size that overruns its segment, causing a BUG_ON assertion failure.
- 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-2026-98868?
CVE-2026-98868 is a denial of service vulnerability in Linux, published on 18 Oct 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: reject a kset that overruns its segment
cache_replay(), the writeback worker and the GC worker read a kset of get_kset_onmedia_size() bytes and advance the position by it. A forged key_num makes that size exceed the segment's remaining space, so the advance walks past the segment and trips the cache_pos_advance() BUG_ON.
Reject a kset whose on-media size exceeds cache_seg_remain() before use.
Which versions are affected by CVE-2026-98868?
How do I fix CVE-2026-98868?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-98868 being exploited?
There is no known exploitation of CVE-2026-98868 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98868, DEBIAN-CVE-2026-98868, GHSA-94mx-pc7x-6h6x, UBUNTU-CVE-2026-98868.