Cisco IOS XR 4.1.2 through 5.1.1 on ASR 9000 devices, when a Trident-based line card is used, allows remote attackers to cause a denial of service (NP chip and line card reload) via malformed IPv6 packets, aka Bug ID CSCun71928.
http://www.securitytracker.com/id/1030400
http://www.securityfocus.com/bid/68005
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140611-ipv6