Firebox and Fireware OS
CVE-2026-86134: Fireware OS Pre-Authentication NULL Pointer Dereference Allows Remote Denial of Service
A NULL pointer dereference vulnerability in the WatchGuard Fireware OS authentication process allows a remote, unauthenticated attacker to crash the management daemon by sending a specially request to the login interface, resulting in a denial of service.
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
A NULL pointer dereference vulnerability in the WatchGuard Fireware OS authentication process allows a remote, unauthenticated attacker to crash the management daemon by sending a specially request to the login interface, resulting in a denial of service.
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.