Cisco IOS 12.2, 12.4, 15.0, 15.2, and 15.3 allows remote attackers to cause a denial of service (device reload) via malformed Common Industrial Protocol (CIP) TCP packets, aka Bug ID CSCun63514.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2015-0662
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150325-cip