Firebox and Fireware OS
CVE-2026-13377: WatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in SIP Proxy Configuration
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS SIP Proxy module allows Stored XSS.
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 12.0 | 12.11.9 or later |
| Fireware OS (Default) 2025.1 | 2026.2.1 or later |
| Fireware OS (Default) 12.0 | 12.12.1 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
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS SIP Proxy module allows Stored XSS. This vulnerability is an additional unmitigated attack path for CVE-2025-6947.
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.