Cisco IOS XE 3.5E and earlier on WS-C3850, WS-C3860, and AIR-CT5760 devices does not properly parse the "request system shell" challenge response, which allows local users to obtain Linux root access by leveraging administrative privilege, aka Bug ID CSCur09815.
https://exchange.xforce.ibmcloud.com/vulnerabilities/98529
http://www.securitytracker.com/id/1031179
http://www.securityfocus.com/bid/70968
http://tools.cisco.com/security/center/viewAlert.x?alertId=36351
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2014-7990