Microsoft has released a Post-Windows NT 4.0 Service Pack 6a Security Rollup Package. Thanks Daniel.
Microsoft has released a Security Rollup Package (SRP) for Windows NT 4.0 that includes the functionality from all security patches released for Windows NT 4.0 since the release of Windows NT 4.0 Service Pack 6a (SP6a). This small, comprehensive rollup of post-SP6a fixes provides an easier mechanism for managing the rollout of security fixes. Applying the SRP does not change the encryption level of your computer.Download
If you add optional services, you must reapply the Windows NT 4.0 service pack and then the SRP.