The get_real_string function in Monkey HTTP Daemon (monkeyd) 0.8.1 and earlier allows remote attackers to cause a denial of service (crash) via an HTTP request with a sequence of "%" characters and a missing Host field.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15187
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-0276
http://www.securityfocus.com/bid/9642
http://monkeyd.sourceforge.net/