The Server in Microsoft Lync Server 2013 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon hang) via a crafted request, aka "Lync Denial of Service Vulnerability."
https://exchange.xforce.ibmcloud.com/vulnerabilities/95547
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-055
http://www.securitytracker.com/id/1030821