It was possible to kill the web server by sending an invalid request with a too long HTTP 1.1 header (Accept-Encoding, Accept-Language, Accept-Range, Connection, Expect, If-Match, If-None-Match, If-Range, If-Unmodified-Since, Max-Forwards, TE, Host) A cracker may exploit this vulnerability to make your web server crash continually or even execute arbirtray code on your system.

upgrade your software or protect it with a filtering reverse proxy