ARMember Premium <= 7.3.1 - Authenticated (Subscriber+) SQL Injection via 'sSortDir_0' Parameter

The ARMember Premium plugin for WordPress is vulnerable to SQL Injection via the 'sSortDir_0' parameter of the `get_private_content_data` AJAX action in all versions up to, and including, 7.3.1. This is due to insufficient sanitization of the user-supplied parameter which is concatenated directly into the ORDER BY clause of an SQL query without a whitelist check. This makes it possible for authenticated attackers, with Subscriber-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. Note: The vulnerability can only be exploited if the "User Private Content" addon is enabled, which is disabled by default..