The Common Internet File System (CIFS) optimization in Cisco Wide Area Application Services (WAAS) 4.0.7 and 4.0.9, as used by Cisco WAE appliance and the NM-WAE-502 network module, when Edge Services are configured, allows remote attackers to cause a denial of service (loss of service) via a flood of TCP SYN packets to port (1) 139 or (2) 445.