WP Forms Connector <= 1.8 - Missing Authorization to Unauthenticated Information Exposure via 'user/list' REST Endpoint

Summary

The WP Forms Connector plugin for WordPress is vulnerable to Information Exposure in all versions up to, and including, 1.8. The plugin registers the REST route wp/v3/user/list/<id> (callback userDetail()) with permission_callback set to '__return_true', and the function's home-grown authentication only verifies that the supplied 'Username' HTTP header maps to an administrator account and that a 'Password' HTTP header is non-empty. It never validates the password with wp_check_password() (unlike the sibling delete_wc_user() function which does). This makes it possible for unauthenticated attackers to retrieve sensitive information for any registered user ID — including the WordPress password hash (user_pass) and email address — by sending a request with a valid administrator login name (commonly the default 'admin') and any arbitrary password value.