What’s Vulnerable › Vulnerabilities

CVE-2026-81851: Fireware OS Heap-Based Buffer Overflow in iked Allows Denial of Service

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-28 · updated 2026-08-28
• Weakness: CWE-122

Description

A heap-based buffer overflow vulnerability in Fireware OS's iked process allows an authenticated administrator to crash the IKE daemon (iked), resulting in a denial of service, by saving a specially crafted configuration.

Affected products

• WatchGuard Fireware OS: from 2025.0 before 2026.2.1; from 12.0 before 12.12.1; from 12.0 before 12.11.9; from 12.0 before 12.5.18 — fixed in 12.11.9, 12.12.1, 12.5.18, 2026.2.1

How to fix

Upgrade to a fixed version: WatchGuard Fireware OS 12.11.9, 12.12.1, 12.5.18, 2026.2.1. Check the vendor advisory for mitigations.

References

• https://psirt.watchguard.com/CVE-2026-81851

Get alerted when CVE-2026-81851 or the next vulnerability affects your stack