User Frontend <= 4.3.13 - Reflected Cross-Site Scripting via 'field_attr[required]' Parameter

The User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'field_attr[required]' parameter in all versions up to, and including, 4.3.13 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. The nonce check on the wpuf_get_child_cat AJAX action is not an effective security barrier because the wpuf_nonce value is publicly localized to every anonymous visitor of any page containing a WPUF shortcode, making it freely harvestable by an unauthenticated attacker.