The Remote Desktop Protocol (RDP) implementation in Microsoft Windows 7 SP1, Windows 8, Windows 8.1, and Windows Server 2012 Gold and R2 allows remote attackers to cause a denial of service (memory consumption and RDP outage) by establishing many RDP sessions that do not properly free allocated memory, aka "Remote Desktop Protocol (RDP) Denial of Service Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-030