Groundhogg <= 4.5.14 - Authenticated (Vendor+) SQL Injection via 'tag_query' Parameter

The Groundhogg — CRM, Newsletters, and Marketing Automation plugin for WordPress is vulnerable to generic SQL Injection via the 'tag_query' parameter in all versions up to, and including, 4.5.14 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 vendor-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. Exploitation requires the attacker to trigger the vulnerable Legacy_Contact_Query code path by submitting an unknown filter type (e.g. filters[0][0][type]=force_fallback), which causes a FilterException that dispatches execution away from the modern query handler.