Describe CVE-2021-4350.
What is CVE-2021-4350?
The Frontend File Manager plugin for WordPress is vulnerable to Unauthenticated HTML Injection in versions up to, and including, 18.2. This is due to lacking authentication protections on the wpfm_send_file_in_email AJAX action. This makes it possible for unauthenticated attackers to send emails using the site with a custom subject, recipient email, and body with unsanitized HTML content.  This effectively lets the attacker use the site as a spam relay..