A vulnerability in the TCP/IP stack of Cisco Email Security Appliance (ESA), Cisco Web Security Appliance (WSA), and Cisco Secure Email and Web Manager, formerly Security Management Appliance, could allow an unauthenticated, remote attacker to crash the Simple Network Management Protocol (SNMP) service, resulting in a denial of service (DoS) condition. This vulnerability is due to an open port listener on TCP port 199. An attacker could exploit this vulnerability by connecting to TCP port 199. A successful exploit could allow the attacker to crash the SNMP service, resulting in a DoS condition.