Microsoft Support:
April 14, 2026 - KB5084165 Cumulative Update for .NET Framework 3.5 for Windows 11, version 26H1 (build 28000) and later
The April 14, 2026 update installs the complete .NET Framework 3.5 product for Windows 11, version 26H1 (build version 28000) and newer. Unlike traditional cumulative updates that patch individual components, this delivers the full .NET Framework 3.5 product as a standalone installer. It replaces any previously installed version. Before you install this update, see the Prerequisites and Restart requirement sections.Summary
Security ImprovementsCVE-2026-32178 - .NET Framework Remote Code Execution vulnerability
This security update addresses a remote code execution vulnerability detailed in CVE-2026-32178.
CVE-2026-32203 - .NET Framework Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-32203.
CVE-2026-32226 - .NET Framework Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-32226.
CVE-2026-23666 - .NET Framework Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-23666.
CVE-2026-26171 - .NET Framework Security Feature Bypass vulnerability
This security update addresses a security feature bypass vulnerability detailed in CVE-2026-26171.
CVE-2026-33116 - .NET Framework Information Disclosure vulnerability
This security update addresses an information disclosure vulnerability detailed in CVE-2026-33116.
Quality and Reliability Improvements
There are no new Quality and Reliability Improvements in this update.
Known issues in this update
Microsoft is not currently aware of any issues in this update.How to get this update
Install this update| Release Channel | Available | Next Step |
|---|---|---|
| Microsoft Update | Yes | None. This update will be downloaded and installed automatically from Microsoft Update. |
| Microsoft Update Catalog | Yes | To get the standalone package for this update, go to the Microsoft Update Catalog website. |
| Windows Server Update Services (WSUS) | Yes | WSUS admins will need to download and synchronize the new ".NET Framework 3.5" product. For more information, go here: Setting up Update Synchronizations | Microsoft Learn" Product: Windows 11, version 26H1 Classification: Security Updates |
File information
For a list of the files that are provided in this update, download the file information for cumulative update.
Prerequisites
To apply this update, you must have .NET Framework 3.5 installed.Restart requirement
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.Information about uninstallation
Uninstalling this update removes .NET Framework 3.5 entirely. It does not revert to a previously installed version. To rollback, uninstall the current version and reinstall a prior version from the Microsoft Update Catalog. Refer to the side navigation history for links to previous versions. Source:
