CVE-2026-80548 s390/vfio_ccw: Selectively expand io_mutex
A race condition in the s390 vfio_ccw driver could lead to system instability or denial of service due to improper mutex handling.
- 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-2026-80548?
CVE-2026-80548 is a high-severity vulnerability in Linux, published on 26 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:
s390/vfio_ccw: Selectively expand io_mutex
The io_mutex was defined to serialize the io_regions, but then has also sort of been associated with the I/O themselves because of the close relationship they share.
With the handful of races that are possible, the choices are either to: A) expand the scope of io_mutex to close these remaining windows, or B) reduce the scope of io_mutex to just io_region, and introduce a new lock mechanism for the remaining I/O resources
This patch implements A, since B brings with it a lot more interactions that would need to be tracked and kept in a correct hierarchy. It also takes advantage of the workqueue element for cp_free() that now gets called out of fsm_notoper(), which could be invoked out of an interrupt context and thus cannot acquire a mutex itself.
Which versions are affected by CVE-2026-80548?
How do I fix CVE-2026-80548?
Apply the vendor's patch.
Is CVE-2026-80548 being exploited?
There is no known exploitation of CVE-2026-80548 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80548, DEBIAN-CVE-2026-80548, GHSA-ccx7-24wp-j32x, UBUNTU-CVE-2026-80548.