EnvíaloSimple: Email Marketing y Newsletters <= 2.3 - Cross-Site Request Forgery to Arbitrary File Upload

The EnvíaloSimple: Email Marketing y Newsletters plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 2.3. This is due to missing or incorrect nonce validation on the gallery_add function. This makes it possible for unauthenticated attackers to upload malicious files via a forged request granted they can trick a site administrator into performing an action such as clicking on a link. The Cross-Site Request Forgery was patched in 2.4, however, nothing was done about the ability to upload arbitrary files.