CVE intelligence

CVE-2026-63940

Vulnerability intelligence

Published Jul 19, 2026Sources checked Sep 12, 2026

9.3CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-63940 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.

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-2026-63940?

In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Ignore Port I/O requests of length '0' Explicitly ignore Port I/O requests of length '0' (or count '0'), so that setting up the software scratch area (and other code) doesn't have to worry about underflowing the length, and to allow for WARNing on trying to configure the scratch area with len==0.