The HTTP daemon in the Cisco Unified IP Phone, when the Extension Mobility feature is enabled, allows remote authenticated users of other phones associated with the same CUCM server to eavesdrop on the physical environment via a CiscoIPPhoneExecute message containing a URL attribute of an ExecuteItem element that specifies a Real-Time Transport Protocol (RTP) audio stream.
http://www.vupen.com/english/advisories/2007/4036
http://www.securityfocus.com/bid/26668
http://www.hack.lu/pres/hacklu07_Remote_wiretapping.pdf
http://www.cisco.com/en/US/products/products_security_response09186a0080903a6d.html
http://securitytracker.com/id?1019006