Microsoft took the rare step of issuing security fixes for both the server and desktop versions of Windows that are long out of support, so you know this is serious.
The vulnerability (CVE-2019-0708) is in the Remote Desktop Services component built into all versions of Windows. RDP, formerly known as Terminal Services, itself is not vulnerable. CVE-2019-0708 is pre-authentication and requires no user interaction, meaning any future malware could self-propagate from one vulnerable machine to another.
CVE-2019-0708 affects Windows XP, Windows 7, Windows Server 2003, Windows Server 2008 R2, and Windows Server 2008. It does not impact Microsoft’s newest operating systems; Windows 8 through 10 and Windows Server 2012 through 2019 are not affected.