CVE-2026-80858 fuse: publish io-uring queues with release semantics
A race condition in the Linux kernel FUSE io-uring implementation allows concurrent access to uninitialized memory, potentially causing crashes or code execution.
- 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-2026-80858?
CVE-2026-80858 is a 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: publish io-uring queues with release semantics
fuse_uring_create_queue() initializes a fuse_ring_queue and then publishes the pointer into ring->queues[qid] with WRITE_ONCE() under the fch->lock. There are several readers that may concurrently be fetching that pointer locklessly and then deferencing it.
WRITE_ONCE() doesn't ensure ordering of the queue's field initialization before the ring->queues[qid] pointer assignment. The queue must be published with smp_store_release() so the field initialization is guaranteed to happen before.
Readers in paths where the read may happen concurrently with the store need to use READ_ONCE() because any race involving a plain access is undefined.
Which versions are affected by CVE-2026-80858?
How do I fix CVE-2026-80858?
Apply the vendor's patch.
Is CVE-2026-80858 being exploited?
There is no known exploitation of CVE-2026-80858 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80858, DEBIAN-CVE-2026-80858, GHSA-4ch4-gxg4-33mh, UBUNTU-CVE-2026-80858.