In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Use the active VMCB's MSR bitmap when checking if MSR is intercepted… (CVE-2026-98716)

The vulnerability involved KVM's SVM implementation in the Linux kernel incorrectly assuming that the MSR permission bitmap in use was always vmcb02's bitmap when L2 virtualization was active. Instead, KVM uses msrpm02 only if L1 wants to intercept MSR accesses, requiring merging msprm01 with msrpm12. The patch changes the code to use the active VMCB's MSR bitmap directly, avoiding stale or incorrect bitmap references and improving accuracy in MSR interception checks.

Incorrect use of the MSR bitmap could lead to improper handling of MSR interceptions in nested virtualization scenarios, potentially allowing unintended MSR accesses or failures in interception enforcement. However, no known exploits are reported in the wild for this issue.

A fix has been implemented in the Linux kernel to correctly use the active VMCB's MSR bitmap. Users should update to the patched kernel version once available. No additional mitigation steps are indicated.