Drupal 5.x before 5.3 does not apply its Drupal Forms API protection against the user deletion form, which allows remote attackers to delete users via a cross-site request forgery (CSRF) attack.
https://www.redhat.com/archives/fedora-package-announce/2007-October/msg00328.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/37268
http://www.securityfocus.com/bid/26119
http://secunia.com/advisories/27352