CVE-2026-64513

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the KVM x86 implementation where the TPR THRESHOLD field in the VMCS is not correctly updated during certain PPR updates. When apic update ppr() is called and no deliverable interrupts are pending, it fails to raise KVM REQ EVENT, leaving kvm lapic update cr8 intercept() and vmx update cr8 intercept() uncalled before VM entry. This results in a stale TPR THRESHOLD value. On older platforms or during nested virtualization on hypervisors that do not support virtual-interrupt delivery (such as Hyper-V), this inconsistency can trigger a VM entry failure with hardware error 0x7. The issue is primarily related to the handle tpr below threshold() function.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.