Heap-based buffer overflow in Null HTTP Server 0.5.0 and earlier allows remote attackers to execute arbitrary code via a negative value in the Content-Length HTTP header.
http://www.iss.net/security_center/static/10160.php
http://freshmeat.net/releases/97910/
http://archives.neohapsis.com/archives/bugtraq/2002-09/0284.html