Groundhogg <= 4.5.4 - Authenticated (Custom+) SQL Injection via 'after' Parameter

The Groundhogg — CRM, Newsletters, and Marketing Automation plugin for WordPress is vulnerable to generic SQL Injection via the 'after' parameter in all versions up to, and including, 4.5.4 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers, with Sales Manager-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. The AJAX handler wp_ajax_groundhogg_get_contacts_table has its capability check commented out and performs no nonce verification, meaning any authenticated user regardless of role can reach the vulnerable code path.