CVE-2026-80554 s390/vfio_ccw: Limit the number of channel program segments
A missing limit on channel program segments in the Linux kernel s390 vfio-ccw driver allows attackers to cause a denial of service via recursive processing.
- 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-2026-80554?
CVE-2026-80554 is a critical denial of service 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: Limit the number of channel program segments
The processing of channel programs, and the CCWs within them, is done recursively. As such, there is an arbitrary (but not architectural) limit to the number of CCWs that can exist in a single channel program.
The vfio-ccw logic breaks these channel programs into segments whenever it encounters a Transfer-In-Channel (TIC) CCW, and the combined number of segments count towards the global limit. Impose an equivalent limit to the number of segments until such logic can be made non-recursive.
Which versions are affected by CVE-2026-80554?
How do I fix CVE-2026-80554?
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-2026-80554 being exploited?
There is no known exploitation of CVE-2026-80554 in the wild and no public exploit code.
Sources
Also known as AZL-97772, BELL-CVE-2026-80554, DEBIAN-CVE-2026-80554, GHSA-42gq-4mc2-p2hw, UBUNTU-CVE-2026-80554.