The Happy Addons for Elementor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘ha-ia-content-button’ parameter in all versions up to, and including, 3.10.9 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.