Juniper Junos OS before 12.1X46-D50 on SRX Series devices reverts to "safe mode" authentication and allows root CLI logins without a password after a failed upgrade to 12.1X46, which might allow local users to gain privileges by leveraging use of the "request system software" command with the "partition" option.
http://www.securitytracker.com/id/1036307
http://www.securityfocus.com/bid/91757
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10753