CVE-2026-74646 misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke
A race condition in the Linux kernel fastrpc driver allows list corruption during interrupted invokes, potentially causing system crashes or denial of service.
- 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-2026-74646?
CVE-2026-74646 is a high-severity vulnerability in Linux, published on 22 Aug 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:
misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke
When an invoke is interrupted by a signal, wait_for_completion_interruptible() returns -ERESTARTSYS and fastrpc_internal_invoke() moves every buffer from fl->mmaps onto cctx->invoke_interrupted_mmaps. This list_del()/list_add_tail() walk runs without holding fl->lock, the lock that serialises fl->mmaps in fastrpc_req_mmap() and fastrpc_req_munmap() everywhere else.
Take fl->lock around the move, matching every other fl->mmaps accessor.
Which versions are affected by CVE-2026-74646?
How do I fix CVE-2026-74646?
Apply the vendor's patch.
Is CVE-2026-74646 being exploited?
There is no known exploitation of CVE-2026-74646 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74646, DEBIAN-CVE-2026-74646, GHSA-487q-3fxv-jwrm, UBUNTU-CVE-2026-74646.