Multiple cross-site scripting (XSS) vulnerabilities in vtiger CRM before 5.2.1 allow remote attackers to inject arbitrary web script or HTML via (1) the username (aka default_user_name) field or (2) the password field in a Users Login action to index.php, or (3) the label parameter in a Settings GetFieldInfo action to index.php, related to modules/Settings/GetFieldInfo.php.