The DHCPv6 implementation in Cisco IOS XR allows remote attackers to cause a denial of service (process hang) via a malformed packet, aka Bug ID CSCul80924.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2014-3283
http://www.securitytracker.com/id/1030259
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2014-3270