The POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications plugin for WordPress is vulnerable to time-based SQL Injection via the selected parameter in all versions up to, and including, 2.9.3 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers with administrator access or higher to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.