Memory leak in the Cisco Tunneling Control Protocol (cTCP) encapsulation feature in Cisco IOS 12.4, when an Easy VPN (aka EZVPN) server is enabled, allows remote attackers to cause a denial of service (memory consumption and device crash) via a sequence of TCP packets.
https://exchange.xforce.ibmcloud.com/vulnerabilities/49417
http://www.vupen.com/english/advisories/2009/0851
http://www.securitytracker.com/id?1021895
http://www.securityfocus.com/bid/34246
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90469.shtml
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90459.shtml