The Fancy Product Designer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'output_format' parameter in all versions up to, and including, 6.5.2 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 the Pro Export/Genius feature to be enabled on the site, as the vulnerable fpd_pr_export AJAX action is only registered when that feature is active.