CVE-2026-63940

CRITICAL 9.3CVE-2026-63940 · Published 19/07/2026 · updated 30/10/2026

In short

CVE-2026-63940 is a CRITICAL (CVSS 9.3) vulnerability.
Chance of exploitation in the next 30 days (EPSS): 0.19%, higher than 8.2% of all vulnerabilities.
No patched version is listed yet: follow the vendor's advisory in References.

Package	Affected versions	Patched versions
—	No affected product versions are listed for this vulnerability yet.

Description

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.

References

git.kernel.org/stable/c/2254972d4d69e279ba4e87bf0968eb08ad0d3c92 · Patch
git.kernel.org/stable/c/3988bd2723de407ae90fa7a6f6029b4e60238c58 · Patch
git.kernel.org/stable/c/3b6035bc6bff20e89752ce4358bc4c9a9d5883f2 · Patch
git.kernel.org/stable/c/bbd3a27e4f99fdcad82d12d79c04a95dff1ff70b · Patch
git.kernel.org/stable/c/c30cde934c7813b4e3069765dac64ce3d31e34f2 · Patch
git.kernel.org/stable/c/c8aa0a79ab0b23cde4c46ccff78e63be35733e04

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