SMTP Mail <= 1.3.20 is vulnerable to Cross Site Request Forgery (CSRF) vulnerability

The SMTP Mail plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.3.20. This is due to missing or incorrect nonce validation on an unknown function. This makes it possible for unauthenticated attackers to perform an unauthorized action via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.