Critical severity · published Jul 19, 2026
CVE-2026-63940
KVM: SEV: Ignore Port I/O requests of length '0'
9.3
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 8% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
291bd20d5d88814a73d43b55b9428feab2f28094 before bbd3a27e4f99fdcad82d12d79c04a95dff1ff70b; 291bd20d5d88814a73d43b55b9428feab2f28094 before 3b6035bc6bff20e89752ce4358bc4c9a9d5883f2; 291bd20d5d88814a73d43b55b9428feab2f28094 before 2254972d4d69e279ba4e87bf0968eb08ad0d3c92; 291bd20d5d88814a73d43b55b9428feab2f28094 before c30cde934c7813b4e3069765dac64ce3d31e34f2; 291bd20d5d88814a73d43b55b9428feab2f28094 before 3988bd2723de407ae90fa7a6f6029b4e60238c58; 5.11 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63940
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-63940
git.kernel.org
https://git.kernel.org/stable/c/2254972d4d69e279ba4e87bf0968eb08ad0d3c92
git.kernel.org
https://git.kernel.org/stable/c/3988bd2723de407ae90fa7a6f6029b4e60238c58
git.kernel.org
https://git.kernel.org/stable/c/3b6035bc6bff20e89752ce4358bc4c9a9d5883f2
git.kernel.org
https://git.kernel.org/stable/c/bbd3a27e4f99fdcad82d12d79c04a95dff1ff70b
git.kernel.org
https://git.kernel.org/stable/c/c30cde934c7813b4e3069765dac64ce3d31e34f2
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