The Visitor Traffic Real Time Statistics plugin for WordPress is vulnerable to Stored DOM-Based Cross-Site Scripting via 'X-Real-IP' HTTP Header in all versions up to, and including, 8.16 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires no authentication, no nonce, and no capability — the wp_ajax_nopriv_ahcfree_track_visitor endpoint accepts the forged X-Real-IP header from any unauthenticated HTTP request and stores the entity-encoded payload verbatim in the database.