Connect Contact Form 7 and Mailchimp <= 0.9.78.06 - Unauthenticated Stored Cross-Site Scripting via Mailchimp Merge Field Values

The Connect Contact Form 7 and Mailchimp plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Mailchimp Merge Field Values in all versions up to, and including, 0.9.78.06 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. The injected payload is only triggered when a privileged user (Administrator) performs a Contact Lookup for the email address submitted via the CF7 form, meaning execution is deferred until an administrator interacts with the affected entry.