CVE-2026-80891 KVM: s390: pci: Validate AIBV and AISB before pinning guest pages
A guest VM can trigger memory corruption in the Linux kernel KVM s390 PCI handler by providing invalid AIBV or AISB addresses, potentially leading to privilege escalation 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-2026-80891?
CVE-2026-80891 is a memory corruption 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:
KVM: s390: pci: Validate AIBV and AISB before pinning guest pages
The AIBV holds one bit per MSI-X vector for a given function. The size of the bit vector is derived from the NOI and the AIBVO. If the size of the AIBV exceeds a single page boundary, then reject the request as we cannot safely pin the guest AIBV.
Similarly reject the request if the AISB address is not 8-byte aligned as the architecture requires doubleword alignment for the summary bit address. Since the AISBO can address up to 64 bits, the size of the AISB can only be 8 bytes for the function. This also ensures the AISB doesn't exceed a single page boundary.
Which versions are affected by CVE-2026-80891?
How do I fix CVE-2026-80891?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-80891 being exploited?
There is no known exploitation of CVE-2026-80891 in the wild and no public exploit code.
Sources
Also known as AZL-99477, BELL-CVE-2026-80891, DEBIAN-CVE-2026-80891, GHSA-4g2w-hpr2-f26j, UBUNTU-CVE-2026-80891.