CVE-2026-86133: WatchGuard Fireware

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

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 products

• WatchGuard Fireware: from 12.0, before 12.5.21 (fixed in 12.5.21); from 12.12, before 12.12.3 (fixed in 12.12.3); from 2025.0, before 2026.2.3 (fixed in 2026.2.3); from 2026.3, before 2026.3.2 (fixed in 2026.3.2)

Published 2026-09-30. Last modified 2026-10-06.