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 allows Stored XSS via the SIP Proxy module. This vulnerability requires an authenticated administrator session to a locally managed Firebox. This issue affects Firebox: from 12.0 through 12.11.2.