I think you might mean KB4284878 — 2018-06 Security Only Quality Update for Windows Server 2012 R2.
https://support.microsoft.com/en-au/help/4284878/windows-81-update-kb4284878
From the list of files available in the above link, there appears to be several that relate to Active Directory (e.g. Adtschema.dll.mui).
Perhaps the Servers that need this patch are Domain Controllers.
Ian Broadbent