SilverStripe 2.3.x before 2.3.12 and 2.4.x before 2.4.6 allows remote authenticated users with the EDIT_PERMISSIONS permission to gain administrator privileges via a TreeMultiselectField that includes admin groups when adding a user to the selected groups.
https://github.com/silverstripe/sapphire/commit/de1f070
http://www.openwall.com/lists/oss-security/2012/04/30/3
http://www.openwall.com/lists/oss-security/2012/04/30/1
http://doc.silverstripe.org/framework/en/trunk/changelogs/2.4.6
http://doc.silverstripe.org/framework/en/trunk/changelogs/2.3.12