This vulnerability (CVE-2025-1239) affects WatchGuard Fireware OS version 12.0. It is a stored XSS issue in the Blocked Sites list of the Firebox management interface. An attacker with administrator privileges who is authenticated can inject malicious JavaScript code that executes in the context of other management users' sessions, potentially leading to session hijacking or unauthorized actions within the management interface. The CVSS 4.8 score reflects moderate impact with network attack vector, low complexity, and required privileges of high (administrator).

An authenticated administrator can execute arbitrary JavaScript in other administrators' management sessions, potentially compromising the confidentiality and integrity of the management interface. This could allow actions such as session hijacking or manipulation of the management interface, but the impact is limited to authenticated users with high privileges.

No official patch or vendor advisory is currently available for this vulnerability. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is released, restrict administrator access to trusted personnel only and consider monitoring for suspicious activity related to the management interface.