The WP Visitor Statistics (Real Time Traffic) plugin for WordPress is vulnerable to generic SQL Injection via the 'fullRef' parameter in all versions up to, and including, 8.7 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. This is a second-order SQL injection: an unauthenticated attacker submits a crafted referrer URL to the wmcTrack tracking endpoint, which persists the raw unescaped value into the wp_logVisit table, and the injection is triggered when an administrator next views the Traffic Sources dashboard.