The debug console interface on Cisco Small Business SPA300 and SPA500 phones does not properly perform authentication, which allows local users to execute arbitrary debug-shell commands, or read or modify data in memory or a filesystem, via direct access to this interface, aka Bug ID CSCun77435.
https://exchange.xforce.ibmcloud.com/vulnerabilities/94421
http://www.securitytracker.com/id/1030552
http://www.securityfocus.com/bid/68465
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2014-3312