YOP Poll <= 5.7.3 - Reflected Cross-Site Scripting (XSS)

The YOP Poll plugin exposes a number of AJAX requests to the public (see lines 15-40 in th efile yop-poll/inc/admin.php). An XSS vulnerability has been found in at least one of these functions – namely yop_poll_set_wordpress_vote. This function is available to both registered and non-registered users. The fields that are vulnerable are Base64 encoded (see lines 859 to 912 of yop-poll/inc/admin.php), meaning any attacks performed will bypass not only the auto-escaping on quotes performed by WordPress/PHP, but also any XSS-prevention methods implemented by browsers.

http://www.example.com/wp-admin/admin-ajax.php?action=yop_poll_set_wordpress_vote&poll_id=JzthbGVydCgxKTsn