CVE intelligence

CVE-2026-80921

Vulnerability intelligence

Published Sep 9, 2026Sources checked Oct 28, 2026

8.8HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-80921 and is rated High severity with a CVSS score of 8.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 11, 2026

See the Microsoft Security Update Guide for the update that applies to your product.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.1%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-80921?

In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: vsie: zero stale crypto bits

When shadowing crypto access bits from a format0 apcb (crycb 0 or 1), the bits 64..255 are unchanged from whatever is in the vsie page in the crycb and thus in the apcb. This gives a nested guest potential access to a device no longer available.

Zero out the remaining bits.

Source: NVD