The Premium Packages – Sell Digital Products Securely plugin for WordPress is vulnerable to SQL Injection via the 'code' parameter of the POST /wp-json/wpdmpp/v1/cart/coupon REST API endpoint in versions up to, and including, 6.2.0. This is due to insufficient escaping on the user-supplied parameter, which is interpolated directly into a raw SQL query string in the CouponCodes::find() method without use of $wpdb->prepare() or esc_sql(). This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.