Microsoft is now issuing an out-of-band update KB4594440 for devices running Windows 10 version 20H2 and 2004. This rollout represents the second update for the October 2020 Update and the patch number 12 for the May 2020 Update, and it’s a maintenance update that fixes a few problems with the two most recent releases of the operating system.
KB4594440 bumps the version number to build 19041.631 and 19042.631 for version 2004 and 20H2 respectively, and according to the company, fixes authentication and renewal issues for Kerberos ticket after installing the update KB4586781.
Update KB4594440 for Windows 10
Microsoft has announced the KB4594440 update in the Windows support site. If you’re already running the Windows 10 October 2020 Update or May 2020 Update, this update fixes problems with Kerberos authentication related to the PerformTicketSignature registry subkey value in CVE-2020-17049, which was a part of the update KB4586781 released on November 10, 2020.
The following issues might occur on writable and read-only domain controllers (DC):
- Kerberos service tickets and ticket-granting tickets (TGT) might not renew for non-Windows Kerberos clients when PerformTicketSignature is set to 1 (the default).
- Service for User (S4U) scenarios, such as scheduled tasks, clustering, and services for line-of-business applications, might fail for all clients when PerformTicketSignature is set to 0.
- S4UProxy delegation fails during ticket referral in cross-domain scenarios if DCs in intermediate domains are inconsistently updated and PerformTicketSignature is set to 1.
You can download the updates to install them manually for version 20H2 or 2004 from the Microsoft Update Catalog website.
Microsoft is also making available the same fixes for the Windows 10 Anniversary Update (version 1607) as update KB4594441, and once it’s installed, the version number will bump to build 14393.4048.
Download November 2020 update for Windows 10
These updates are available immediately, they’ll download and install automatically, but you can always force the update from Settings > Update & Security > Windows Update and clicking the Check for updates button. You can find more details about the most recent updates in the Windows 10 update history tracker guide.