CVE-2026-89929 KVM: nVM: Ensure INVVPID is emulated on the correct physical CPU
A race condition in KVM nested virtualization allows stale TLB entries, potentially enabling data leakage 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-2026-89929?
CVE-2026-89929 is a high-severity vulnerability in Linux, published on 16 Sep 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: nVM: Ensure INVVPID is emulated on the correct physical CPU
When emulating INVVPID, KVM executes INVVPID on the physical CPU using vpid02 (instead of the L1 assigned VPID), after doing some validations on the operands. However, it is possible that the physical CPU KVM executes INVVPID on is different from the CPU L2 is running on.
For example, in the following scenario: - L2 runs on CPU #1 and exits to L1 (vmx->nested.vmcs02.cpu=1) - L1 migrates to CPU #2 and executes INVVPID - KVM executes INVVPID on CPU #2 - L1 migrates back to CPU #1 and runs L2 (vmx->nested.vmcs02.cpu=1)
The TLB entries on CPU #1 are never invalidated, because INVVPID was executed on CPU #2, and vmcs02 never ran on a different pCPU (i.e. vmx_vcpu_load_vmcs() will *not* request KVM_REQ_TLB_FLUSH).
Ensure that INVVPID is being executed on the same pCPU that L2 last ran on, and if not, fallback to clearing last_vpid=0 to trigger a full VPID flush on the next nested VM-Enter (as KVM will detect L1 using a different VPID for L2). If L2 ends up running on a different pCPU, KVM will flush the TLB anyway through vmx_vcpu_load_vmcs().
Which versions are affected by CVE-2026-89929?
How do I fix CVE-2026-89929?
Apply the vendor's patch.
Is CVE-2026-89929 being exploited?
There is no known exploitation of CVE-2026-89929 in the wild and no public exploit code.
Sources
Also known as AZL-101277, BELL-CVE-2026-89929, DEBIAN-CVE-2026-89929, GHSA-78pj-hm8w-chf6, UBUNTU-CVE-2026-89929.