Bug 2461489 (CVE-2026-31591)

Summary: CVE-2026-31591 kernel: KVM: SEV: Lock all vCPUs when synchronzing VMSAs for SNP launch finish
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) component. This vulnerability allows a local user in userspace to manipulate or run a virtual CPU (vCPU) while its state is being synchronized during the Secure Nested Paging (SNP) launch process. This improper synchronization can lead to corruption of the vCPU state or, in the worst case, cause the host kernel to crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-04-24 15:04:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: SEV: Lock all vCPUs when synchronzing VMSAs for SNP launch finish

Lock all vCPUs when synchronizing and encrypting VMSAs for SNP guests, as
allowing userspace to manipulate and/or run a vCPU while its state is being
synchronized would at best corrupt vCPU state, and at worst crash the host
kernel.

Opportunistically assert that vcpu->mutex is held when synchronizing its
VMSA (the SEV-ES path already locks vCPUs).
Comment 1 Keith Grant 2026-04-24 18:57:50 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042415-CVE-2026-31591-4148@gregkh/T