The Linux kernel’s KVM module for AMD SVM incorrectly keeps the CR8 write interception flag set when the Advanced Virtual Interrupt Controller (AVIC) is enabled or disabled. While this alone only reduces performance, it becomes fatal when combined with a known TPR synchronization bug, causing the virtual processor’s TPR to diverge from the host’s hardware TPR. For Windows guests this divergence can trigger hard crashes or severe instability, and the flaw is a classic example of improper resource management and failure to recognize a fatal condition, reflected in CWE‑821.

The vulnerability exists in all Linux kernel releases that have not incorporated the commit that explicitly clears CR8 write interception when AVIC state changes. It affects KVM hosts that use the AMD SVM virtualization technology with AVIC enabled. Any distribution running a kernel version prior to the included commits remains affected, regardless of the specific distribution.

The CVSS score is 5.5 and the EPSS score indicates less than 1% probability of exploitation. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector is local or system-level; an adversary must control the hypervisor or influence AVIC configuration or trigger CR8 writes. Once exploited, the result is a crash or severe instability of guests that depend on correct TPR management, especially Windows; VMX mode is unaffected.