CVE-2026-80921
Description
A flaw was found in the Linux kernel's KVM s390 Virtual Shared Inter-Partition Emulation (VSIE) component. When shadowing crypto access bits from a format0 apcb, stale crypto bits were not properly cleared. This oversight could allow a nested guest to potentially access a device that should no longer be available, leading to unauthorized information disclosure or access to resources.
Statement
This vulnerability is rated as Important because an unprivileged nested guest could retain unauthorized access to cryptographic coprocessor resources, potentially compromising sensitive cryptographic data and device isolation. The issue exclusively impacts IBM Z (s390x) systems deploying KVM nested virtualization with cryptographic adapter sharing enabled. Deployments on non-s390x hardware architectures and systems that do not execute nested KVM guests on s390x are not affected.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | N/A | 8.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
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