Microsoft issues out-of-band patch for Windows Server sign-in bug

Microsoft logo suspended above a conference floor

Microsoft has issued an out-of-band patch for Windows Server to fix a problem that could potentially stop remote desktop users logging into the system.

The flaw causes performance issues with Windows Server, which would result either in a slow sign-in process, general slowness, or at worst a black screen, Microsoft said.

Windows Server 2019 is at risk, and Microsoft has published KB5010196 to address this edition. The bug also affects Windows Server 2012 Release 2, which the company has addressed with KB5010215.

Also affected are Window Server 2022 and 2016, which the company said it would address in the coming days.

The bug stemmed from the KB5008218 update that Microsoft released during a regular Patch Tuesday update on December 14. This update introduced some security changes for Windows.

The out-of-band updates will not install automatically as part of the Windows Update service, meaning that administrators must install them manually by importing it into the Windows Server Update Service (WSUS). They can get the Windows Server 2019 patch by visiting the Microsoft Update Catalog website. Windows Server 2012 Release 2 users can go here.


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The latest updates are cumulative, and the Windows Server 2019 update inherits three other less urgent Windows issues identified by Microsoft. This includes errors for devices using Asian language packs, and a temporary problem starting the Windows Cluster Service that disappears when rebooting after approximately 20 minutes. There is also an issue with versions of Windows Server used as Key Management Services hosts that might prevent some client Windows 10 operating systems from activating. The company will fix these in future releases, it said.

Out-of-band patches for Windows Server are rare. Microsoft issued one in November last year, addressing a bug in Windows Server when used as a domain controller. The flaw prevented servers from authenticating legitimate users who tried to access resources using a single sign-on token.

Danny Bradbury

Danny Bradbury has been a print journalist specialising in technology since 1989 and a freelance writer since 1994. He has written for national publications on both sides of the Atlantic and has won awards for his investigative cybersecurity journalism work and his arts and culture writing. 

Danny writes about many different technology issues for audiences ranging from consumers through to software developers and CIOs. He also ghostwrites articles for many C-suite business executives in the technology sector and has worked as a presenter for multiple webinars and podcasts.