The vulnerability arises in the KVM SVM module of the Linux kernel when AVIC is inhibited while a Level‑2 guest is active. In this state, the kernel updates the x2APIC MSR intercepts for the Level‑1 guest as if AVIC had always been disabled. The result is that the guest can read most of the host’s APIC state, send arbitrary interrupts, and change task priority, which can trivially disrupt the host. The effect is a local denial‑of‑service from the VM to the host.

All Linux kernel configurations that enable the KVM SVM hypervisor and AVIC (Advanced Virtual Interrupt Controller) are affected. The issue is present in kernels that have not yet applied the patch that enforces proper MSR intercept updates when AVIC is disabled during an active L2 session.

The CVSS score is 8.2, the EPSS score is < 1%, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is a local user controlling a Level‑1 virtual machine that can trigger the AVIC inhibition logic while a Level‑2 guest is running. An attacker can then issue IPI sequences that cause the host to service spurious interrupts or consume CPU resources, leading to a denial‑of‑service condition. No public exploit has been disclosed, but the ability to crash the host makes the risk significant for environments running KVM SVM with AVIC enabled.