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Released April 14, 2026 Updated April 28, 2026, to include a known issue.
Summary of what's new in this release
Security improvements
CVE-2026-32178 – Remote Code Execution vulnerability
This security update addresses a remote code execution vulnerability detailed in CVE-2026-32178.
CVE-2026-32203 – Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-32203.
CVE-2026-32226 – Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-32226.
CVE-2026-23666 – Denial of Service vulnerability
This security update addresses a denial-of-service vulnerability detailed in CVE-2026-23666.
CVE-2026-26171 – Security Feature Bypass vulnerability
This security update addresses a security feature bypass vulnerability detailed in CVE-2026-26171.
CVE-2026-33116 – Information Disclosure vulnerability
This security update addresses an information disclosure vulnerability detailed in CVE-2026-33116.
Quality and reliability improvements
.NET Runtime
Addresses an issue to add verification logic for ClickOnce to support SHA384 and SHA512. (Applies to: .NET Framework 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1)
Addresses an issue in cases where the Arm64 CLR could crash when code generates and catches a NullReferenceException within the same function. (Applies to: .NET Framework 4.8.1)
Addresses an issue to update operating system calls for compliance with current standards. (Applies to: .NET Framework 4.8.1)
WCF
Addresses an issue with running a WCF NamedPipe service inside a Win32 app container when running on Windows 11 or Windows Server 2025. (Applies to: .NET Framework 4.8.1)
Known issues in this release
This update might fail to install when applied through DISM to an offline Windows 10 IoT Enterprise LTSC 21H2 image. A fix for this issue will be included in an upcoming .NET Framework update.
Summary tables
The following table outlines the updates in this release.
| Product version | Cumulative update |
|---|---|
| Windows 11, version 26H1 | |
| .NET Framework 4.8.1 | 5082421 |
| Windows 11, version 25H2 | |
| .NET Framework 3.5, 4.8.1 | 5082417 |
| Windows 11, version 24H2 | |
| .NET Framework 3.5, 4.8.1 | 5082420 |
| Microsoft server operating system, version 24H2 | |
| .NET Framework 3.5, 4.8.1 | 5082417 |
| Microsoft server operating system, version 23H2 | |
| .NET Framework 3.5, 4.8.1 | 5082418 |
| Windows 11, version 22H2 and Windows 11, version 23H2 | |
| .NET Framework 3.5, 4.8.1 | 5082424 |
| Windows Server 2022 | 5084071 |
| .NET Framework 3.5, 4.8 | 5082427 |
| .NET Framework 3.5, 4.8.1 | 5082425 |
| Windows 10, version 22H2 | 5084068 |
| .NET Framework 3.5, 4.8 | 5082426 |
| .NET Framework 3.5, 4.8.1 | 5082419 |
| Windows 10, version 21H2 | 5084067 |
| .NET Framework 3.5, 4.8 | 5082426 |
| .NET Framework 3.5, 4.8.1 | 5082419 |
| Windows 10 1809 and Windows Server 2019 | 5084066 |
| .NET Framework 3.5, 4.7.2 | 5082413 |
| .NET Framework 3.5, 4.8 | 5082414 |
| Windows 10 1607 and Windows Server 2016 | |
| .NET Framework 3.5, 4.6.2, 4.7, 4.7.1, 4.7.2 | 5082198 |
| .NET Framework 4.8 | 5082411 |
The following table is for earlier Windows and Windows Server versions for Security and Quality Rollup updates.
| Product version | Security and quality rollup |
|---|---|
| Windows Server 2012 R2 | 5084070 |
| .NET Framework 3.5 | 5082406 |
| .NET Framework 4.6.2, 4.7, 4.7.1, 4.7.2 | 5082402 |
| .NET Framework 4.8 | 5082404 |
| Windows Server 2012 | 5084069 |
| .NET Framework 3.5 | 5082398 |
| .NET Framework 4.6.2, 4.7, 4.7.1, 4.7.2 | 5082400 |
| .NET Framework 4.8 | 5082403 |
The operating system rows list a KB that's used for update-offering purposes. When the operating system KB is offered, the applicability logic determines the specific .NET Framework updates that will be installed. Updates for individual .NET Framework versions are installed based on the version of .NET Framework that's already present on the device. Because of this, the operating system KB is not expected to be listed as an installed update on the device. The expected updates to be installed are the .NET Framework specific version updates listed in the preceding table.
This 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.
| Product version | .NET Framework 3.5 product update |
|---|---|
| Windows 11, version 26H1 | 5084165 |
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