The anti-spam scanner on Cisco Email Security Appliance (ESA) devices 3.3.1-09, 7.5.1-gpl-022, and 8.5.6-074 allows remote attackers to bypass intended e-mail restrictions via a malformed DNS SPF record, aka Bug IDs CSCuu35853 and CSCuu37733.
http://www.securitytracker.com/id/1032582
http://www.securityfocus.com/bid/75181
http://tools.cisco.com/security/center/viewAlert.x?alertId=39339