This was scavanged from the debian bug report: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=329156 gnome-pty-helper can be made to write utmp/wtmp records with arbitrary DISPLAY (host) settings. I am not sure if it can be tricked into erasing existing records.
This issue may also affect RHEL2.1 and RHEL3
Security team review 20051026 decided this flaw is not a security risk -> WONTFIX