CVE-2026-98720 KVM: nVMX: Force MSR bitmap refresh if runtime eVMCS controls are modified
A guest VM can read or write the host's Task Priority Register due to a missing MSR bitmap refresh, potentially leading to information disclosure or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98720?
CVE-2026-98720 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
KVM: nVMX: Force MSR bitmap refresh if runtime eVMCS controls are modified
Force a refresh of the vmcs02 MSR bitmap during nested VM-Enter if the runtime eVMCS controls (pin, primary, secondary, etc.) are being updated. If L1 isn't intercepting TPR writes, runs L2 with TPR virtualization, and then runs the same L2 with TPR virtualization disabled, KVM will fail to refresh msr_bitmap02 and leave TPR in passthrough mode even though TPR virtualization is disabled. I.e. failure to refresh the bitmap lets L2 (or L1 by proxy) read and write L0's TPR.
Which versions are affected by CVE-2026-98720?
How do I fix CVE-2026-98720?
Apply the vendor's patch.
Is CVE-2026-98720 being exploited?
There is no known exploitation of CVE-2026-98720 in the wild and no public exploit code.
Sources
Also known as AZL-109266, BELL-CVE-2026-98720, DEBIAN-CVE-2026-98720, GHSA-6822-57w6-j97m, UBUNTU-CVE-2026-98720.