The Divi theme for WordPress is vulnerable to Stored Cross-Site Scripting via the redirect_url parameter of the et_pb_contact_form shortcode in all versions up to, and including, 4.27.6. This is due to the redirect_url attribute being sanitized with esc_attr() instead of esc_url() before being rendered into the data-redirect_url HTML data attribute. Additionally, redirect_url is absent from the hardcoded $url_options array in class-et-builder-element.php, so it does not receive esc_url_raw() sanitization during shortcode parsing. After a successful form submission, client-side JavaScript reads this data attribute and passes it directly to window.location.href, executing arbitrary JavaScript from a javascript: URI. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that execute whenever a user submits the contact form.