The Cisco Firewall Services Module (FWSM) 2.x, 3.1 before 3.1(16), 3.2 before 3.2(13), and 4.0 before 4.0(6) for Cisco Catalyst 6500 switches and Cisco 7600 routers allows remote attackers to cause a denial of service (traffic-handling outage) via a series of malformed ICMP messages.