The menuBar feature in rxvt 2.7.8 allows attackers to modify menu options and execute arbitrary commands via a certain character escape sequence that inserts the commands into the menu.
http://www.securityfocus.com/bid/6947
http://www.redhat.com/support/errata/RHSA-2003-055.html
http://www.redhat.com/support/errata/RHSA-2003-054.html
http://www.mandrakesoft.com/security/advisories?name=MDKSA-2003:034
http://www.iss.net/security_center/static/11416.php
http://marc.info/?l=bugtraq&m=104612710031920&w=2
http://archives.neohapsis.com/archives/vulnwatch/2003-q1/0093.html