The kernel bug occurs when the system toggles SVM (x86 virtualization) on a CPU that supports Branch Sampling (BRS) and Last Branch Record (LBR). The code path that reprograms PerfMon event selectors incorrectly attempts to enable BRS even when the CPU lacks this feature, writing to a deprecated MSR bit. This results in a general protection fault that can crash or panic the kernel, causing a denial of service. This vulnerability corresponds to CWE-358. The flaw is a hardware feature misuse and does not directly lead to data leakage or privilege escalation. It is an internal kernel bug that can be triggered by normal operations involving virtualization or perf events.

All Linux kernel installations that run on AMD CPUs with support for either BRS or LBR are potentially affected. The specific kernel versions impacted are not listed in the data, but the fix is present in any kernel revision that includes the described commit. Users running older kernels prior to that commit, regardless of distribution, should consider upgrading.

The vulnerability is not listed in the CISA KEV catalog but has an EPSS score of <1% and a CVSS score of 5.5, indicating a low likelihood of exploitation. The attack vector is inferred to be local, requiring the kernel to execute the SVM toggle path; a remote attacker could not trigger the fault without privileged access. Because the fault causes a kernel crash, the risk assessment is moderate: it can be used to cause a denial of service but is unlikely to be exploited in the wild. Applying the vendor patch removes the defect and eliminates the crash path.