Live › vulnerability › CVE-2026-98720
Go to dashboardThe Linux kernel's KVM nested VMX code fails to refresh the vmcs02 MSR bitmap when eVMCS controls change between nested VM entries. A guest VM can then read and write the host's TPR (task priority register) directly.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Hosts running the Linux kernel with KVM and nested virtualization (Hyper-V enlightened VMCS, L1 hypervisors running L2 guests) are the systems where this applies. The sources do not say which kernel versions are affected or which configurations beyond nested VMX are required. Hosts without KVM nested virtualization can skip it.
No product ranges from the sources yet.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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