VMware VirtualCenter 2.5 before Update 2 and 2.0.2 before Update 5 relies on client-side "enabled/disabled functionality" for access control, which allows remote attackers to determine valid user names by enabling functionality in the GUI and then making an "attempt to assign permissions to other system users."
https://exchange.xforce.ibmcloud.com/vulnerabilities/44425
http://www.vupen.com/english/advisories/2008/2363
http://www.vmware.com/support/vi3/doc/releasenotes_vc202u5.html
http://www.vmware.com/security/advisories/VMSA-2008-0012.html
http://www.securitytracker.com/id?1020693
http://www.securityfocus.com/bid/30664
http://www.securityfocus.com/archive/1/495386/100/0/threaded
http://www.insomniasec.com/advisories/ISVA-080812.1.htm