The TrueBooker – Appointment Booking and Scheduler System plugin for WordPress is vulnerable to generic SQL Injection via the 'alldata[truebooker_user]' parameter in all versions up to, and including, 1.2.2 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL 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. The check_ajax_referer() nonce guard does not constitute an authentication or authorization barrier because the nonce is exposed to unauthenticated visitors on TrueBooker front-end booking pages; exploitation additionally requires that the required booking fields (category, service, person, date, and time slot) be present in the alldata POST parameter so that execution reaches the vulnerable SQL query branch.