CVE-2026-80891
Received Received - Intake

KVM: s390 PCI MSI-X Validation Flaw

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

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.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80891
EUVD
EUVD-2026-71641

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves improper validation of AIBV and AISB addresses in the KVM s390 PCI subsystem. The AIBV bit vector size is checked against page boundaries, and the AISB address alignment is verified for doubleword requirements. If these validations fail, the system rejects the request to prevent unsafe guest page pinning.

Detection Guidance

This vulnerability is specific to the Linux kernel's KVM s390 PCI implementation. Detection requires checking kernel logs for related errors or examining the KVM module for the described validation failures. Commands like dmesg | grep -i kvm or journalctl -k | grep -i kvm may help identify issues.

Impact Analysis

This vulnerability could allow a malicious guest to cause a denial of service by triggering improper memory handling in the KVM s390 PCI subsystem. It may lead to system instability or crashes if exploited.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it is a low-level kernel issue related to memory management in KVM for s390 systems. Compliance impacts would depend on system configuration and usage rather than this specific vulnerability.

Mitigation Strategies

Update the Linux kernel to a patched version that resolves this issue. Monitor kernel logs for AIBV or AISB validation failures. If using KVM on s390, ensure guest configurations do not trigger the described boundary conditions.

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