The Squid package in Red Hat Linux 5.2 and 6.0, and other distributions, installs cachemgr.cgi in a public web directory, which allows remote attackers to use it as an intermediary to connect to other systems.
https://exchange.xforce.ibmcloud.com/vulnerabilities/2385
http://www.securityfocus.com/bid/2059
http://www.redhat.com/support/errata/archives/rh52-errata-general.html#squid
http://www.redhat.com/support/errata/RHSA-2005-489.html
http://www.redhat.com/support/errata/RHSA-1999-025.html
http://www.redhat.com/archives/fedora-announce-list/2005-May/msg00025.html