The MetForm – Contact Form, Survey, Quiz, & Custom Form Builder for Elementor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'mf_form_id' Widget Setting in all versions up to, and including, 4.1.8 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The payload bypasses Elementor's save-time wp_kses_post filter because it contains no HTML tags, and MetForm's own str_replace transformation of script tags into JavaScript template literal expressions provides an additional delivery path.
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.8/widgets/form.php#L143
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.8/utils/util.php#L605
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.8/controls/form-picker-utils.php#L45
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.4/widgets/form.php#L143
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.4/utils/util.php#L605
https://plugins.trac.wordpress.org/browser/metform/tags/4.1.4/controls/form-picker-utils.php#L45