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.
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A critical vulnerability (CVSS 9.3) has been identified in the Linux kernel KVM subsystem affecting systems using AMD SEV. An integer underflow in Port I/O handling could lead to memory corruption, potentially compromising host-to-guest isolation.
Relevant roles
Severity
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HEPSS
Technical 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.