Open redirect vulnerability in Blue Coat ProxySG 6.5 before 6.5.8.8 and 6.6 and Advanced Secure Gateway (ASG) 6.6 might allow remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a base64-encoded URL in conjunction with a "clear text" one in a coaching page, as demonstrated by "http://www.%humbug-URL%.local/bluecoat-splash-API?%BASE64-URL%."