MailChimp Forms by MailMunch <= 3.1.7 - Cross-Site Request Forgery via Multiple AJAX actions

The MailChimp Forms by MailMunch plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 3.1.7. This is due to missing nonce validation on several of the plugin's functions, such as delete_email(), delete_widget(), change_email_status(), and settings_page(). This makes it possible for unauthenticated attackers to delete widgets and change or delete arbitrary email subscriber records via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.