The guestbook CGI program in ICQ Web Front service for ICQ 2000a, 99b, and others allows remote attackers to cause a denial of service via a URL with a long name parameter.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2000-0560
http://archives.neohapsis.com/archives/ntbugtraq/2000-q2/0218.html