The WAAS Express feature in Cisco IOS 15.1 and 15.2 allows remote attackers to cause a denial of service (memory consumption or device reload) via crafted transit traffic, aka Bug ID CSCtt45381.
https://exchange.xforce.ibmcloud.com/vulnerabilities/74428
http://www.securitytracker.com/id?1026862
http://www.securityfocus.com/bid/52751
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120328-mace