The TCP reassembly feature in Cisco IOS XE 3.7 before 3.7.3S and 3.8 before 3.8.1S on 1000 ASR devices allows remote attackers to cause a denial of service (device reload) via large TCP packets that are processed by the (1) NAT or (2) ALG component, aka Bug ID CSCud72509.
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20131030-asr1000