The EAP-FAST authentication module in Cisco Secure Access Control Server (ACS) 4.x before 4.2.1.15.11, when a RADIUS server configuration is enabled, does not properly parse user identities, which allows remote attackers to execute arbitrary commands via crafted EAP-FAST packets, aka Bug ID CSCui57636.
http://www.securitytracker.com/id/1028958
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130828-acs