CVE-2026-80857 fuse: wait for FR_FINISHED on abort_on_kill to prevent use-after-free
A use-after-free in the Linux kernel FUSE subsystem allows local attackers to execute arbitrary code or escalate privileges.
- 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-2026-80857?
CVE-2026-80857 is an use after free vulnerability in Linux, published on 4 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:
fuse: wait for FR_FINISHED on abort_on_kill to prevent use-after-free
The abort_on_kill path in request_wait_answer() calls fuse_abort_conn() and returns without waiting for FR_FINISHED. If fuse_dev_do_write() is concurrently processing the same request (FR_LOCKED set), the caller frees req->args while it is still being accessed, causing a use-after-free.
Fix this by jumping to the existing wait_event(FR_FINISHED) instead of returning early. The wait will not hang because fuse_abort_conn() ensures all requests are ended.
Which versions are affected by CVE-2026-80857?
How do I fix CVE-2026-80857?
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-2026-80857 being exploited?
There is no known exploitation of CVE-2026-80857 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80857, DEBIAN-CVE-2026-80857, GHSA-3r92-fq36-p33j, UBUNTU-CVE-2026-80857.