CVE-2026-86133: Fireware OS Pre-Authentication Integer Underflow in iked Allows Remote Denial of Service

Published Sep 29, 2026

Updated

An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker who has completed the initial IKEv2 handshake to crash the iked process by sending a specially crafted encrypted IKEv2 message, resulting in a denial of service.

Affected Software

1 affected component

WatchGuard Fireware OS

Remediation

Recommended actions to resolve this vulnerability, in priority order.

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

DescriptionSeverityWeakness

Frequently Asked Questions

What does an attacker need before they can trigger the denial of service?

The attacker must complete the initial IKEv2 handshake and then send a specially crafted encrypted IKEv2 message to the iked daemon.

What is the operational impact of successful exploitation?

Successful exploitation crashes the iked process, causing a denial of service.