Critical 9.3Published Jul 19, 2026

CVE-2026-63940KVM: SEV: Ignore Port I/O requests of length '0'

Updated under an hour ago (Oct 28, 2026, 3:40 PM ET)

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Exploited in the last 30 days

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.

CVSS: 9.3 CRITICAL (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness (CWE): CWE-190
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Oct 21, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 291bd20d5d88814a73d43b55b9428feab2f28094 before bbd3a27e4f99fdcad82d12d79c04a95dff1ff70b; 291bd20d5d88814a73d43b55b9428feab2f28094 builds before 3b6035bc6bff20e89752ce4358bc4c9a9d5883f2; from 291bd20d5d88814a73d43b55b9428feab2f28094 before 2254972d4d69e279ba4e87bf0968eb08ad0d3c92; from 291bd20d5d88814a73d43b55b9428feab2f28094 before c30cde934c7813b4e3069765dac64ce3d31e34f2; from 291bd20d5d88814a73d43b55b9428feab2f28094 before 3988bd2723de407ae90fa7a6f6029b4e60238c58	CNA record
linux linux_kernel linux:linux_kernel	from 5.11 before 6.6.160; from 6.7 before 6.12.95; from 6.13 before 6.18.35; from 6.19 before 7.0.12; 7.1; 7.1; 7.1; 7.1; and 1 more ranges	NVD

References

References

https://git.kernel.org/stable/c/bbd3a27e4f99fdcad82d12d79c04a95dff1ff70b	patch
https://git.kernel.org/stable/c/3b6035bc6bff20e89752ce4358bc4c9a9d5883f2	patch
https://git.kernel.org/stable/c/2254972d4d69e279ba4e87bf0968eb08ad0d3c92	patch
https://git.kernel.org/stable/c/c30cde934c7813b4e3069765dac64ce3d31e34f2	patch
https://git.kernel.org/stable/c/3988bd2723de407ae90fa7a6f6029b4e60238c58	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.