CVE-2026-81851: WatchGuard Fireware OS

Medium severity, CVSS 6.9. EPSS: 0.4% chance of exploitation in the next 30 days.

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 (fixed in 2026.2.1); from 12.0, before 12.12.1 (fixed in 12.12.1); from 12.0, before 12.11.9 (fixed in 12.11.9); from 12.0, before 12.5.18 (fixed in 12.5.18)

Published 2026-08-28. Last modified 2026-08-28.