The Chatbot plugin for WordPress is vulnerable to Missing Authorization in versions up to, and including, 8.5.9 via the wpcs_send_email() AJAX handler. This is due to the wpcs_send_email() function being registered on both wp_ajax_wpcs_send_email and wp_ajax_nopriv_wpcs_send_email with no nonce verification, capability check, or rate limiting, while forwarding attacker-controlled recipient, subject, and body directly to wp_mail(). This makes it possible for unauthenticated attackers to send arbitrary emails to any recipient from the site's domain, enabling spam, phishing, and abuse that can lead to the site's IP/domain being blacklisted.