Cotonti CSRF in admin.config.php allows unauthorized configuration changes

Cotonti 1.0.0 (master branch, commit f43f1fc3) is vulnerable to Cross-Site Request Forgery in the administration configuration handler. In system/admin/admin.config.php, the configuration update action ('a=update') processes POST data via cot_config_update_options without calling cot_check_xg to validate the anti-CSRF token (the 'x' parameter), unlike other admin handlers (e.g. admin.structure.php, admin.cache.php).