The MetForm Pro plugin for WordPress is vulnerable to Improper Input Validation in all versions up to, and including, 3.9.7 This is due to the payment integrations (Stripe/PayPal) trusting a user-submitted calculation field value without recomputing or validating it against the configured form price. This makes it possible for unauthenticated attackers to manipulate the payment amount via the 'mf-calculation' field in the form submission REST request granted there exists a specific form with this particular configuration.

The MetForm Pro plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Quiz feature in all versions up to, and including, 3.9.6 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.