Microsoft: Lync 2013 Information Disclosure Vulnerability
An information disclosure vulnerability exists in Lync 2013. An attacker who exploited it could read arbitrary files on the victim's machine. To exploit the vulnerability, an attacker needs to instantiate a conference and modify the meeting link with malicious content and send the link to a victim. The update addresses the vulnerability by changing how the URL is being resolved.
Microsoft Lync Server 2013