The WP-Chatbot for Messenger plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 4.9. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to overwrite the site's MobileMonkey API token and company ID options, which can be used to hijack chatbot configuration and redirect visitor conversations to an attacker-controlled MobileMonkey account.