Ultimate Member <= 2.13.1 - Missing Authorization to Unauthenticated Sensitive Profile Field Disclosure via Member Directory Field Privacy Bypass

The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 2.13.1 This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to view privacy-restricted member profile field values — including fields explicitly configured as owner-only, members-only, or role-restricted — by querying the publicly accessible wp_ajax_nopriv_um_get_members endpoint. The nonce required by the endpoint ('um-frontend-nonce') is emitted to all unauthenticated visitors via wp_localize_script, meaning it provides no meaningful access control and any anonymous visitor can satisfy the endpoint's authentication requirements.