Unknown vulnerability in the privilege system in Drupal 4.4.0 through 4.6.0, when public registration is enabled, allows remote attackers to gain privileges, due to an "input check" that "is not implemented properly."
http://secunia.com/advisories/15372
http://marc.info/?l=bugtraq&m=111782257601422&w=2
http://archives.neohapsis.com/archives/fulldisclosure/2005-06/0010.html