Cisco IOS 15.5(3)M on Integrated Services Router (ISR) 800, 819, and 829 devices allows remote attackers to cause a denial of service (memory consumption) via crafted TCP packets on the SSH port, aka Bug ID CSCuu13476.
http://www.securitytracker.com/id/1036141
http://www.securityfocus.com/bid/91322
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160620-isr