The WP Maps plugin for WordPress is vulnerable to time-based blind SQL Injection via the 'location_id' parameter in all versions up to, and including, 4.9.1. This is due to the plugin's database abstraction layer (FlipperCode_Model_Base::is_column()) treating user input wrapped in backticks as column names, bypassing the esc_sql() escaping function. Additionally, the wpgmp_ajax_call AJAX handler (registered for unauthenticated users via wp_ajax_nopriv) allows calling arbitrary class methods including wpgmp_return_final_capability, which passes the unsanitized location_id GET parameter directly to a database query. 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.