Firebox and Fireware OS
CVE-2026-86132: Fireware OS Pre-Authentication Integer Underflow in iked Allows Denial of Service
An integer underflow vulnerability in the WatchGuard Fireware OS IKEv2 daemon (iked) allows a remote, unauthenticated attacker to crash the process by sending a specially crafted encrypted IKEv2 message negotiated with an AES-GCM cipher suite.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Fireware OS (Default) 2026.3 | 2026.3.2 or later |
| Fireware OS (Default) 2025.0 | 2026.2.3 or later |
| Fireware OS (Default) 12.0 | 12.12.3 or later |
| Fireware OS (T15/T35) 12.0 | 12.5.21 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An integer underflow vulnerability in the WatchGuard Fireware OS IKEv2 daemon (iked) allows a remote, unauthenticated attacker to crash the process by sending a specially crafted encrypted IKEv2 message negotiated with an AES-GCM cipher suite.
Am I affected?
This vulnerability affects Firebox systems configured with a branch office VPN with IKEv2 to a dynamic peer or a mobile VPN with IKEv2
Exploitation
WatchGuard is not aware of any exploitation of this vulnerability in the wild.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.