Microsoft released fixes for a critical Remote Code Execution vulnerability, CVE-2019-0708, in Remote Desktop Services – formerly known as Terminal Services – that affects some older versions of Windows.
The Remote Desktop Protocol (RDP) itself is not vulnerable. This vulnerability is pre-authentication and requires no user interaction.
The vulnerability is ‘wormable’, meaning that any future malware that exploits this vulnerability could propagate from vulnerable computer to vulnerable computer in a similar way as the WannaCry malware spread across the globe in 2017.
While there has been no observed exploitation of this vulnerability, it is highly likely that malicious actors will write an exploit for this vulnerability and incorporate it into their malware.
It is important that affected systems are patched as quickly as possible. Vulnerable in-support systems include Windows 7, Windows Server 2008 R2, and Windows Server 2008. Out-of-support systems include Windows 2003 and Windows XP.
Microsoft Security Update Guide