KVM Vulnerability in Linux Kernel Affecting Virtual Machine Performance

CVE-2026-64513

What is CVE-2026-64513?

A critical issue has been identified in the Linux kernel's KVM (Kernel-based Virtual Machine) component, specifically related to the handling of virtual TPR (Task Priority Register) thresholds. When the TPR_THRESHOLD field in the VMCS is not accurately computed during PPR updates, it can lead to suboptimal VM performance and potential VM entry failures. This oversight is particularly pronounced in older platforms and nested virtualization environments lacking support for virtual-interrupt delivery. In these cases, the failure to execute necessary intercept routines can manifest as hardware errors, disrupting the reliability of virtual machines. By resolving this issue in the Linux kernel, improved handling of VM exits and interrupt requests is ensured, thereby enhancing overall virtual machine operation.

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