The Happy Addons for Elementor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'ha_page_custom_js' parameter in all versions up to, and including, 3.20.3 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, despite the intended role restriction of Custom JS to Administrators.
CWE-79