Cisco IOS XE 3.4 before 3.4.2S and 3.5 before 3.5.1S on 1000 ASR devices allows remote attackers to cause a denial of service (device reload) via malformed ICMP error packets associated with a (1) TCP or (2) UDP session that is under inspection by the Zone-Based Firewall (ZBFW) component, aka Bug ID CSCtt26470.