April 8, 2025—KB5055521 (OS Build 14393.7969)
Applies To
Windows 10, version 1607, all editions Windows Server 2016, all editionsRelease Date:
4/8/2025
Version:
OS Build 14393.7969
For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. For an overview of Windows 10, version 1607, see its update history page.
Important Windows updates do not install Microsoft Store application updates. If you are an enterprise user, see Microsoft Store apps - Configuration Manager. If you are a consumer user, see Get updates for apps and games in Microsoft Store.
Summary
This cumulative update contains security and quality improvements. The following is a summary of the key issues that this update addresses. The bold text within the brackets indicates the item or area of the change we are documenting.
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This update addresses security issues for your Windows operating system.
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[Daylight Saving Time (DST)] Update for the Aysen region in Chile to support the government DST change order in 2025. For more information about DST changes, see the Daylight Saving Time & Time Zone Blog.
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[OS Security] After installing this update or a later Windows update, a new %systemdrive%\inetpub folder will be created on your device. This folder should not be deleted regardless of whether Internet Information Services (IIS) is enabled on the target device. This behavior is part of changes that increase protection and does not require any action from IT admins and end users. For more information, see CVE-2025-21204.
If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.
For more information about security vulnerabilities, please refer to the new Security Update Guide website and the April 2025 Security Updates.
Known issues
Symptoms
Audit Logon/Logoff events in the local policy of the Active Directory Group Policy might not show as enabled on the device even if they are enabled and working as expected. This can be observed in the Local Group Policy Editor or Local Security Policy, where local audit policies show the "Audit logon events" policy with Security Setting of "No auditing".
This issue might only manifest as a reporting inconsistency. It’s possible that logon events are correctly being audited on the device. However, the “Audit logon events” policy will reflect that this is not the case. Home users are unlikely to be affected by this issue, as logon auditing is generally only necessary in enterprise environments.
Workaround
Adjustments to the Windows registry will prevent this issue. For information about how to make these adjustments, see Security auditing settings are not applied to Windows Vista-based and Window Server 2008-based computers when you deploy a domain-based policy.
Next Steps
Microsoft is working on a resolution and will provide more information when it is available.
How to get this update
Before you install this update
To install any Windows 10, version 1607 cumulative update released on or after January 14, 2025, you must first install the latest Servicing Stack Update (SSU). If your device or offline image does not have the latest SSU installed, you cannot install this update.
Caution Until you install the SSU, this update will not be offered to your device. To reduce your security risk, install the SSU as soon as possible.
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If you use Windows Update, the latest SSU (KB5055661) will be offered to you automatically. After the latest SSU is installed, you will be able to install this update.
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If you use Windows Update for Business, the latest SSU (KB5055661) will be offered to you automatically. After the latest SSU is installed, you will be able to install this update.
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If you use the Update Catalog, you must download and install the latest SSU (KB5055661). After the latest SSU is installed, you will be able to install this update.
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If you are a Windows Server Update Services (WSUS) administrator, you must approve SSU KB5055661 and this update KB5055521.
For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.
Install this update
To install this update, use one of the following Windows and Microsoft release channels.
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This update will be downloaded and installed automatically from Windows Update and Microsoft Update. |
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This update will be downloaded and installed automatically from Windows Update for Business in accordance with configured policies. |
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To get the standalone package for this update, go to the Microsoft Update Catalog website. |
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This update will automatically sync with Windows Server Update Services (WSUS) if you configure Products and Classifications as follows: Product: Windows 10 Classification: Security Updates |
File information
A list of the files that are included in this update are provided in a CSV (Comma delimited) (*.csv) file. The file can be opened in a text editor such as Notepad or in Microsoft Excel.
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