GestSup versions prior to 3.2.60 contain a pre-authentication stored cross-site scripting (XSS) vulnerability in the API error logging functionality. By sending an API request with a crafted X-API-KEY header value (for example, to /api/v1/ticket.php), an unauthenticated attacker can cause attacker-controlled HTML/JavaScript to be written to log entries. When an administrator later views the affected logs in the web interface, the injected content is rendered without proper output encoding, resulting in arbitrary script execution in the administrator’s browser session.