Published Aug 26, 2026Sources checked Oct 28, 2026
9.3CRITICALCVSS out of 10
What this means
Review the available evidence
CVE-2026-80551 and is rated Critical severity with a CVSS score of 9.3. 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: Oct 2, 2026
Release Notes
Vendor-listed releases
6.6.157.1-1
CISA KEVNot listedBased on the latest collected catalog
EPSS0.2%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-80551?
In the Linux kernel, the following vulnerability has been resolved:
s390/vfio_ccw: Ensure first IDAW remains constant
The first IDAW in a list does not need to be on a 2K/4K boundary like all others, and so is read separately to accurately calculate the size of the buffer needed to read the full IDAL.
Verify that the address found in the first IDAW is unchanged between reads, to ensure a consistent set of IDAWs being worked with.