---
title: "CVE-2026-89915: Linux Kernel KVM arm64 - Authentication Bypass"
description: "Linux kernel KVM arm64 contains a broken authentication caused by flawed VM-wide VNCR mapping counter logic, letting attackers potentially bypass TLB invalidation guarantees, exploit requires specific CPU and VM conditions."
url: https://panop.io/threat-heartbeat/CVE-2026-89915/
---

# CVE-2026-89915 Linux Kernel KVM arm64 - Authentication Bypass

Linux kernel KVM arm64 contains a broken authentication caused by flawed VM-wide VNCR mapping counter logic, letting attackers potentially bypass TLB invalidation guarantees, exploit requires specific CPU and VM conditions.

CVSS base score 9.3 /10

Critical

CISA KEV

Not listed

Public exploit

None known

EPSS

0.19% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89915)

## Details

Type

Authentication Bypass

Impact

Privilege Escalation

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Published

16 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-89915](https://nvd.nist.gov/vuln/detail/CVE-2026-89915)
- [https://git.kernel.org/stable/c/5453b85c7ebb605febac3df42021f9471663f051](https://git.kernel.org/stable/c/5453b85c7ebb605febac3df42021f9471663f051)
- [https://git.kernel.org/stable/c/87c2bbf189829dce4aaada8f82e3d54ccc037976](https://git.kernel.org/stable/c/87c2bbf189829dce4aaada8f82e3d54ccc037976)
- [https://git.kernel.org/stable/c/c55bc773b6e814406658fae7dc5c15f639ed816e](https://git.kernel.org/stable/c/c55bc773b6e814406658fae7dc5c15f639ed816e)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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