Cisco Unified Communications Manager IM and Presence Service 9.1(1) produces different returned messages for URL requests depending on whether a username exists, which allows remote attackers to enumerate user accounts via a series of requests, aka Bug ID CSCur63497.
https://exchange.xforce.ibmcloud.com/vulnerabilities/98786
http://www.securitytracker.com/id/1031240
http://www.securityfocus.com/bid/71173
http://tools.cisco.com/security/center/viewAlert.x?alertId=36467
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2014-8000