The Ultra Addons for Contact Form 7 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Database module in versions 3.5.11 to 3.5.19 due to insufficient input sanitization and output escaping. The unfiltered field names are stored alongside the sanitized values. Later, the admin-side AJAX endpoint ajax_get_table_data() returns those raw names as JSON column headers, and the client-side DataTables renderer injects them directly into the DOM without any HTML encoding. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
https://wordpress.org/plugins/ultimate-addons-for-contact-form-7/#developers