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… (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.
AI Analysis
Technical Summary
The Linux kernel contained a vulnerability in the KVM SEV module where Port I/O requests of length zero were not explicitly ignored. This could lead to underflow conditions or improper handling in the software scratch area configuration. The vulnerability has been addressed by explicitly ignoring such zero-length Port I/O requests, improving robustness and enabling warnings for misconfiguration.
Potential Impact
The vulnerability could cause improper handling of zero-length Port I/O requests in the KVM SEV component, potentially leading to underflow or misconfiguration issues. However, no known exploits exist in the wild, and the impact details such as privilege escalation or denial of service are not specified.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to explicitly ignore Port I/O requests of length zero in the KVM SEV module. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; therefore, check the vendor advisory for current remediation guidance.
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… (CVE-2026-63940)
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 v3.1
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel contained a vulnerability in the KVM SEV module where Port I/O requests of length zero were not explicitly ignored. This could lead to underflow conditions or improper handling in the software scratch area configuration. The vulnerability has been addressed by explicitly ignoring such zero-length Port I/O requests, improving robustness and enabling warnings for misconfiguration.
Potential Impact
The vulnerability could cause improper handling of zero-length Port I/O requests in the KVM SEV component, potentially leading to underflow or misconfiguration issues. However, no known exploits exist in the wild, and the impact details such as privilege escalation or denial of service are not specified.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to explicitly ignore Port I/O requests of length zero in the KVM SEV module. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; therefore, check the vendor advisory for current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-jx39-q92m-wf39
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63940"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27aa2a4a8d598912e88b
Added to database: 07/19/2026, 19:38:18 UTC
Last enriched: 07/19/2026, 20:04:28 UTC
Last updated: 07/20/2026, 21:52:10 UTC
Views: 11
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