The issue is related to insufficient protection of internal data in the WordPress content management system, allowing remote attackers to gain unauthorized access to protected information. Specifically, WordPress does not properly restrict which user fields are searchable via the REST API, enabling unauthenticated attackers to discern the email addresses of users who have published public posts on an affected website via an Oracle style attack. The Popup Builder WordPress plugin through version 4.1.15 does not sanitize and escape some of its settings, which could allow high-privilege users, such as admins, to perform Stored Cross-Site Scripting attacks.