CVE-2013-6968
Cisco WebEx Training Center provides different error messages for registration attempts depending on whether the e-mail address exists, which allows remote attackers to enumerate attendees via a series of requests, aka Bug ID CSCul36003.
Date published : 2013-12-14
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2013-6968
http://tools.cisco.com/security/center/viewAlert.x?alertId=32147