MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder < 4.3.4 - Unauthenticated Stored Cross-Site Scripting via Form Field Values

Description

The MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Form Field Values in all versions up to, and including, 4.3.3 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.