The Login No Captcha reCAPTCHA plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the $_SERVER['PHP_SELF'] superglobal in all versions up to, and including, 1.8.0. This is due to the authenticate() function storing the unsanitized output of basename($_SERVER['PHP_SELF']) in the login_nocaptcha_error WordPress option when a login attempt is made from a non-standard login page (e.g., xmlrpc.php). The admin_notices() function then echoes this stored value directly into the admin dashboard HTML without escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute when an administrator with a whitelisted IP address visits the WordPress dashboard within 30 seconds of the attack.