PAM configuration file for rlogin in Red Hat Linux 6.1 and earlier includes a less restrictive rule before a more restrictive one, which allows users to access the host via rlogin even if rlogin has been explicitly disabled using the /etc/nologin file.
Xsession in Red Hat Linux 6.1 and earlier can allow local users with restricted accounts to bypass execution of the .xsession file by starting kde, gnome or anotherlevel from kdm.
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.