Multiple cross-site scripting (XSS) vulnerabilities in Phorum 5.0.17a and earlier allow remote attackers to inject arbitrary web script or HTML via (1) the username parameter to register.php or (2) a signature of a logged-in user in "My Control Center," which is not properly handled by control.php.
SQL injection vulnerability in follow.php in Phorum 5.0.12 and earlier allows remote authenticated users to execute arbitrary SQL command via the forum_id parameter.