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.