Cisco Firewall Services Module (aka FWSM) 3.1 before 3.1(21), 3.2 before 3.2(22), 4.0 before 4.0(16), and 4.1 before 4.1(7), when IPv6 is used, allows remote attackers to cause a denial of service (memory corruption and module crash or hang) via vectors that trigger syslog message 302015, aka Bug ID CSCti83875.