CVE-2026-89916

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: Make VNCR invalidation participate in MMU invalidation retry

A VNCR TLB invalidation can occur on one vcpu while another vcpu is

faulting in this same page. Without correctly handling this, we can

end up with the following scenario:

- vcpu A walks the PTs to translate VNCR

- before vcpu A is able to grab the MMU lock to insert the TLB,

vcpu B updates the S1 PTs with an invalid entry, and issues

a TLBI S1E2 for this VA

- vcpu A inserts the TLB for something that is now invalid

This isn't a new problem, and we manage S2 by having the MMU notifier

to bump up mmu_invalidate_seq on invalidation so that the fault can be

replayed.

We can perform something similar here, and extend invalidate_vncr_va() to

update the same counter, clearly indicating that the context has

changed under our feet. This is safe as the invalidation always happen

while holding the MMU lock for write, and that we sample the sequence

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References