CRLF injection vulnerability in the tornado.web.RequestHandler.set_header function in Tornado before 2.2.1 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via crafted input.
http://www.tornadoweb.org/documentation/releases/v2.2.1.html
http://www.securityfocus.com/bid/53612
http://www.openwall.com/lists/oss-security/2012/05/18/6