Firebox and Fireware OS
CVE-2026-13371: WatchGuard Firebox Management Web UI Denial of Service via Unsafe Deserialization
An authenticated administrator can trigger a denial-of-service condition in the Fireware Management Web UI by sending malformed or crafted data to the put_data endpoint, which performs unsafe deserialization of the attacker-supplied input.
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) 2025.1 | 2026.2.1 or later |
| Fireware OS (Default) 12.0 | 12.12.1 or later |
| Fireware OS (EUCC) 12.0 | 12.11.9 or later |
| Fireware OS (T15/T35) 12.0 | 12.5.19 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An authenticated administrator can trigger a denial-of-service condition in the Fireware Management Web UI by sending malformed or crafted data to the put_data endpoint, which performs unsafe deserialization of the attacker-supplied input.
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.