All about Microsoft Patchday January 2025

Microsoft released security updates for Windows 10 and Windows 11 on January Patch Day. The new builds fix bugs and security holes – and there are a number of improvements.

Regular security and maintenance updates

The updates are recommended for all users as they close security gaps and introduce improvements. The patches start for all users of the still fully supported versions of Windows 10 and Windows 11. Microsoft lists all changes and available variants for desktop and server in the Windows update history and has published the corresponding knowledge base articles.

We have compiled the available updates. The updates can be obtained via the Windows Update function, via the Microsoft Update Catalog or via Windows Server Update Services (WSUS).

Security-related changes

Microsoft combines the latest Servicing Stack Update (SSU) for the operating system with the latest cumulative update (LCU). If you use an older LCU update, you must first carry out the separately offered SSU updates. A little tip: At the start of the release, the KB articles may not yet be directly accessible from Microsoft.

But that usually changes quite quickly. About searching in Microsoft Update Catalog but you can already find all the new versions. The following list will help you check whether you have the latest version installed. There you will find the latest build numbers for the individual Windows versions. Check your installed version number with the keyboard command Windows + R to open the Run dialog. Entering “WinVer” then calls up the version display.

Windows 10 versions:

• Version 21H2, 22H2 KB5049981 (Build 19044.5371, 19045.5371)
• Version 1809, KB5050008 (Build 17763.6775)
• Version 1607, Windows Server 2016, KB5049993 (Build 14393.7699)
• Version 1507, KB5050013 (Build 10240.20890)

Windows 11 versions:

• Windows 11 version 24H2, KB5050009 (Build 26100.2894)
• Windows 11 version 22H2 and 23H2 KB5050021 (Build 22621.4751 and 22631.4751)

Microsoft has already summarized the most important changes for the new version. We have translated and summarized the highlights of the updates for you. As usual, there is an article about the patch in the knowledge base.

Highlights Windows 10

This security update includes quality improvements that were part of update KB5048652 (released on December 10, 2024). If you install this KB:

• This update fixes security issues for your Windows operating system.
• Overview of changes in the knowledge base article: KB5049981.

Highlights Windows 11 22H2/23H2

This security update includes improvements that were part of update KB5048685 (released December 10, 2024). If you install this KB:

• This update fixes security issues for your Windows operating system.
• This update expands the list of drivers vulnerable to Bring Your Own Vulnerable Driver (BYOVD) attacks.
• Overview of changes in the knowledge base article: KB5050021.

Windows 11 Servicing Stack Update – 22621.4740 and 22631.4740

• This update makes quality improvements to the Service Stack, the component that installs Windows Updates. Service Stack Updates (SSU) ensure that you have a stable and reliable service stack so that your devices can receive and install Microsoft updates.

Vulnerability details

There were some vulnerabilities in Defender, BitLocker, .Net, Windows Recovery Environment Agent, Windows Registry and File Explorer. The update also addresses security holes in the kernel as well as in the Windows Start Manager, in the remote desktop client and several vulnerabilities in Office. Further information about the fixed security vulnerabilities can be found in Security Update Guide and in the January 2025 security updates.