January 2021 cumulative update: KB4598242/build 19042.746 #KBAlert


Hi all,

First, you may have noticed that the build shown is 19042 only. This is in line with the KB alert policy where the previous build is mentioned up to 60 days after the next feature update is released. For build 19041, the 60-day period ended in December. The next KB alert for 19041 will be sent in coming December when it goes out of support.


January 2021 cumulative update (KB4598242/build 19042.746) is on your way:

January 12, 2021—KB4598242 (OS Builds 19041.746 and 19042.746) (



• Updates to improve security when using external devices, such as game controllers, printers, and web cameras.

• Updates to improve security when Windows performs basic operations.



• Addresses a security vulnerability issue with HTTPS-based intranet servers. After installing this update, HTTPS-based intranet servers cannot, by default, use a user proxy to detect updates. Scans using these servers will fail if you have not configured a system proxy on the clients. If you must use a user proxy, you must configure the behavior using the policy “Allow user proxy to be used as a fallback if detection using system proxy fails.” To ensure the highest levels of security, also use Windows Server Update Services (WSUS) Transport Layer Security (TLS) certificate pinning on all devices. This change does not affect customers who are using HTTP WSUS servers. For more information, see Changes to scans, improved security for Windows devices.

• Addresses a security bypass vulnerability that exists in the way the Printer Remote Procedure Call (RPC) binding handles authentication for the remote Winspool interface. For more information, see KB4599464.

• Security updates to Windows App Platform and Frameworks, Windows Media, Windows Fundamentals, Windows Kernel, Windows Cryptography, Windows Virtualization, Windows Peripherals, and Windows Hybrid Storage Services.