ntop running in web mode allows remote attackers to read arbitrary files via a .. (dot dot) attack.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2000-0701
http://www.securityfocus.com/bid/1550
http://www.redhat.com/support/errata/RHSA-2000-049.html
http://archives.neohapsis.com/archives/bugtraq/2000-07/0459.html