---
id: CVE-2026-86128
title: >-
  A NULL pointer dereference vulnerability in Fireware OS's NetFlow
  packet-processing feature allows a remote, unauthenticated attacker to cause a
  denial of service by sending a specially crafted IPv6 packet.
summary: >-
  A NULL pointer dereference vulnerability in Fireware OS's NetFlow
  packet-processing feature allows a remote, unauthenticated attacker to cause a
  denial of service by sending a specially crafted IPv6 packet.
severity: high
cvss: 8.2
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cwe:
  - CWE-476
vendor: WatchGuard
product: Fireware OS
affected:
  - fireware_os >= 2026.3 < 2026.3.2
  - fireware_os >= 2025.0 < 2026.2.3
  - fireware_os >= 12.0 < 12.12.3
  - fireware_os >= 12.0 < 12.5.21
published: '2026-09-30'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T00:16:36.687'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86128'
references:
  - url: 'https://psirt.watchguard.com/CVE-2026-86128'
    label: 5d1c2695-1a31-4499-88ae-e847036fd7e3
tags:
  - nvd
  - cve.org
cvssSource: cna
ingestedAt: '2026-09-29T23:52:50.549Z'
---

## Overview

A NULL pointer dereference vulnerability in Fireware OS's NetFlow packet-processing feature allows a remote, unauthenticated attacker to cause a denial of service by sending a specially crafted IPv6 packet.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.