MC4WP: Mailchimp for WordPress vulnerabilities

The MC4WP: Mailchimp for WordPress plugin before version 4.15.0 does not prevent request-derived values in its dynamic content tags from being processed as shortcodes when a form is embedded with its block. This allows unauthenticated visitors to execute arbitrary registered shortcodes with attacker-chosen attributes, provided the site owner has added a request-derived tag to the form content and embedded the form with the block rather than the classic shortcode.

The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'data' Dynamic Content Tag in all versions up to and including 4.14.0 due to insufficient input sanitization and output escaping. This allows unauthenticated attackers to inject arbitrary web scripts that execute if they can trick a user into clicking a link.

The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the form response message post meta fields (e.g., 'text_subscribed', 'text_error') in all versions up to, and including, 4.12.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.