CVE intelligence

CVE-2026-89915

Vulnerability intelligence

Published Sep 16, 2026Sources checked Oct 21, 2026

9.3CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-89915 and is rated Critical severity with a CVSS score of 9.3. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-89915?

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

KVM: arm64: Remove VM-wide VNCR mapping counter

The global VNCR mapping counter is used to decide whether an L1 provided VNCR page is mapped in L0 on any CPU at the point of dealing with a TLB invalidation. It is incremented when a mapping is made in the fixmap, and decremented when unmapped.

As it turns out, this tracking has several flaws:

- we are trying to invalidate TLBs, and the mapping is only an opportunistic consequence of the TLB. Checking this counter to decide whether a TLB needs to be invalidated may result in missed invalidations.

- an L1 vcpu invalidating its own TLB (a very likely case) will not succeed in invalidating the VNCR pseudo TLB because that page is not mapped in L0 at this stage.

Given that this tracking fails at delivering the minimum guarantees that are required and is only a performance optimisation, remove it completely.

Source: NVD