The Web Directory Free WordPress plugin before 1.7.0 does not sanitise and escape a parameter before using it in a SQL statement via an AJAX action available to unauthenticated users, leading to a SQL injection with different techniques like UNION, Time-Based and Error-Based.

The Web Directory Free for WordPress is vulnerable to SQL Injection via the ‘post_id’ parameter in versions up to, and including, 1.6.7 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 contributor-level privileges to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.