Researcher Dan Melamed recently discovered an open URL redirection flaw in Facebook that allowed to have a facebook.com link redirect to any website without restrictions. Facebook quick fixed the vulnerability after the Dans report and the payout for the bug is $1,000. An open URL Redirection flaw is generally used to convince a user to click on a trusted link which is specially crafted to take them to an arbitrary website, the target website could be used to serve a malware or for a phishing attack.”]
Source: http://securityaffairs.co/wordpress/19749/hacking/facebook-open-url-redirection.html