xterm, including 192-7.el4 in Red Hat Enterprise Linux and 208-3.1 in Debian GNU/Linux, sets the wrong group ownership of tty devices, which allows local users to write data to other users' terminals.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10421
https://issues.rpath.com/browse/RPL-1396
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=239070
http://www.securityfocus.com/bid/26710
http://www.securityfocus.com/archive/1/477632/100/100/threaded
http://www.securityfocus.com/archive/1/477469/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2007-0701.html
http://support.avaya.com/elmodocs2/security/ASA-2007-490.htm
http://securityreason.com/securityalert/3066
http://secunia.com/advisories/27921
http://secunia.com/advisories/27617