Microsoft WinNT 'Malformed Security Identifier Request' Vulnerability Patch - Version 1 Microsoft has released a patch that eliminates a vulnerability in Microsoft(r) Windows NT(r) 4.0. The vulnerability could allow a malicious user to cause a Windows NT machine to stop responding to requests for service. The patch for this vulnerability is included in the previously-released patch for the 'Syskey Keystream Reuse' vulnerability; customers who have already applied it do not need to take any further action.