Memory leak in the IKEv1 implementation in Cisco IOS 15.1 allows remote attackers to cause a denial of service (memory consumption) via unspecified (1) IPv4 or (2) IPv6 IKE packets, aka Bug ID CSCth81055.
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130327-ike