# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** AZL-99477, BELL-CVE-2026-80891, DEBIAN-CVE-2026-80891, GHSA-4g2w-hpr2-f26j, UBUNTU-CVE-2026-80891

## 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.

## Is CVE-2026-80891 being exploited?

There is no known exploitation of CVE-2026-80891 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80891 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-80891 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-80891/ (Markdown: https://insights.sbomify.com/CVE-2026-80891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80891
- OSV: https://osv.dev/vulnerability/CVE-2026-80891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80891/
Summaries are generated and may contain mistakes; the official description above is the record.