Zope before 2.2.4 allows partially trusted users to bypass security controls for certain methods by accessing the methods through the fmt attribute of dtml-var tags.
http://www.securityfocus.com/bid/3425
http://www.redhat.com/support/errata/RHSA-2001-115.html
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-080.php3