BookingPress Appointment Booking Pro <= 5.7.1 - Unauthenticated SQL Injection via 'store_service_date' Parameter

The BookingPress Appointment Booking Pro plugin for WordPress is vulnerable to SQL Injection via the 'store_service_date' parameter of the bpa_assign_staffmember_to_slots() function in versions up to and including 5.7.1. This is due to the explicit use of stripslashes_deep() on user-supplied POST data before it is interpolated verbatim into a SQL LIKE clause without use of $wpdb->prepare() or any parameterization. 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.