CVE-2026-86128: Fireware OS NULL Pointer Dereference in NetFlow IPv6 Traffic Processing Allows Remote Denial of Service

Q: What does an attacker need to exploit this issue?

The attacker only needs the ability to send a specially crafted IPv6 packet to the affected Fireware OS device. No authentication is required.

Q: What is the likely impact of successful exploitation?

Successful exploitation can cause a denial of service through a NULL pointer dereference in NetFlow packet processing.

Published Sep 29, 2026

Updated

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.

Affected Software

5 affected components

WatchGuard Fireware OS

WatchGuard Fireware>=12.0<12.5.21

WatchGuard Fireware>=12.12<12.12.3

WatchGuard Fireware>=2025.0<2026.2.3

WatchGuard Fireware>=2026.3<2026.3.2

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade Fireware OS to a version that resolves this vulnerability.
Fixed in 2026.3.2
Upgrade
Upgrade Fireware OS to a version that resolves this vulnerability.
Fixed in 2026.2.3
Upgrade
Upgrade Fireware OS to a version that resolves this vulnerability.
Fixed in 12.12.3
Upgrade
Upgrade Fireware OS to a version that resolves this vulnerability.
Fixed in 12.5.21

Event History

Sep 29, 2026

CVE Published

via MITRE·11:05 PM

Data Sourced

via MITRE·11:05 PM

RemedyDescriptionWeakness

Sep 30, 2026

Data Sourced

via NVD·12:16 AM

RemedyDescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

What does an attacker need to exploit this issue?

The attacker only needs the ability to send a specially crafted IPv6 packet to the affected Fireware OS device. No authentication is required.

What is the likely impact of successful exploitation?