The JetEngine plugin for WordPress is vulnerable to SQL Injection via the listing_load_more AJAX action in all versions up to, and including, 3.8.6.1. This is due to the filtered_query parameter being excluded from the HMAC signature validation (allowing attacker-controlled input to bypass security checks) combined with the prepare_where_clause() method in the SQL Query Builder not sanitizing the compare operator before concatenating it into SQL statements. 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, provided the site has a JetEngine Listing Grid with Load More enabled that uses a SQL Query Builder query.