DeepL Pro API translation <= 2.1.4 is vulnerable to Cross Site Request Forgery (CSRF) vulnerability

The DeepL Pro API translation plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.1.4. This is due to missing or incorrect nonce validation on the 'saveSettings' function. This makes it possible for unauthenticated attackers to change plugin settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.