The Mail Mint – Email Marketing, Newsletter, Email Automation & WooCommerce Emails plugin for WordPress is vulnerable to generic SQL Injection via the 'recipients' parameter in all versions up to, and including, 1.24.1 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 administrator-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. This is a second-order SQL injection: the malicious payload is first stored unsanitized via a POST request to /mrm/v1/campaigns/ (bypassing filter_recipients() validation because an int-cast of a string like '1) OR ...' evaluates to a real numeric ID), and is then triggered by a subsequent GET request to /mrm/v1/campaigns/{id} that deserializes the recipients and passes the raw id string through array_column() into the vulnerable query.