CVE-2026-78008: WatchGuard Fireware OS

High severity, CVSS 8.6. EPSS: 0.6% chance of exploitation in the next 30 days.

A buffer overflow vulnerability in the WatchGuard Fireware OS Management Web UI allows an authenticated administrator with network access to cause a denial of service (DoS) condition or potentially execute arbitrary code by sending specially crafted network traffic.

Affected products

• WatchGuard Fireware OS: from 2025.0, before 2026.2.2 (fixed in 2026.2.2); from 12.0, before 12.12.2 (fixed in 12.12.2); from 2026.3, before 2026.3.1 (fixed in 2026.3.1); from 12.0, before 12.5.20 (fixed in 12.5.20)

Published 2026-08-28. Last modified 2026-09-03.