The Simple Membership WP user Import plugin for WordPress is vulnerable to SQL Injection via the ‘orderby’ parameter in versions up to, and including, 1.7 due to insufficient escaping on the user supplied parameter. This makes it possible for authenticated attackers with administrative privileges to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.
https://www.wordfence.com/threat-intel/vulnerabilities/id/6f781533-b633-4452-95bd-c32ed0de2ea9