The User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'display_name' parameter in all versions up to, and including, 4.0.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The payload persists in wp_comments.comment_author independently of the user account, so removing or changing the attacker's display name after the comment is posted does not neutralize the stored script.