The United Kingdom’s National Cyber Security Centre has found a flaw in Windows Remote Desktop Services which allows an attacker to take over or elevate privileges on a Windows computer (not Windows 10).

It is severe enough that Microsoft has issued an out-of-band fix for older versions of Windows.

For Windows 7 and Windows Server 2008, along with a description of the problem, Microsoft offers workarounds and mitigations, along with downloads to repair the problem.

portal.msrc.microsoft.com

Downloads to repair the problem in Windows XP (all versions) and Windows Server 2003 may be found here.

support.microsoft.com

Microsoft considers the potential exploit to be “critical” for all versions of Windows listed.