An NC-25986 issue was discovered in the Logging subsystem of Sophos XG Firewall with SFOS before 17.0.3 MR3. An unauthenticated user can trigger a persistent XSS vulnerability found in the WAF log page (Control Center -> Log Viewer -> in the filter option "Web Server Protection") in the webadmin interface, and execute any action available to the webadmin of the firewall (e.g., creating a new user, enabling SSH, or adding an SSH authorized key). The WAF log page will execute the "User-Agent" parameter in the HTTP POST request.