The Popup Maker – Boost Sales, Conversions, Optins, Subscribers with the Ultimate WP Popup Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via values[Name] Parameter in all versions up to, and including, 1.24.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The wp_kses sanitization applied on output is insufficient in this context because HTML entities within allowed attribute values survive normalization intact and are later evaluated by the jQuery(link.attr('href')) sink in wp-admin/js/common.js when a contextual help tab anchor is clicked.