KB5082417: .NET Framework 3.5 and 4.8.1 Cumulative Update for Windows 11 25H2 and Server 24H2 (April 2026)
April 14, 2026 security and reliability update for .NET Framework 3.5 and 4.8.1 on Windows 11 version 25H2 and Microsoft server operating system 24H2.
Summary
This is the April 14, 2026 cumulative security and reliability update for .NET Framework 3.5 and 4.8.1, targeting Windows 11 version 25H2 and Microsoft server operating system 24H2. It addresses six CVEs - covering remote code execution, denial of service, security feature bypass, and information disclosure - plus one quality fix. Microsoft recommends applying it as part of regular maintenance. Source: Microsoft Support
Improvements and fixes
- Patches a remote code execution vulnerability in .NET Framework tracked as CVE-2026-32178.
- Patches a denial-of-service vulnerability in .NET Framework tracked as CVE-2026-32203.
- Patches a second denial-of-service vulnerability in .NET Framework tracked as CVE-2026-32226.
- Patches a third denial-of-service vulnerability in .NET Framework tracked as CVE-2026-23666.
- Addresses a security feature bypass vulnerability in .NET Framework tracked as CVE-2026-26171.
- Addresses an information disclosure vulnerability in .NET Framework tracked as CVE-2026-33116.
- Resolves an issue where a Windows Communication Foundation (WCF) NamedPipe service fails when running inside a Win32 app container on Windows 11 or Windows Server 2025.
Known issues
Microsoft lists no known issues for this update at the time of writing.
How to get this update
KB5082417 is available through multiple channels. Windows Update and Microsoft Update will download and install it automatically - no manual steps are required. Windows Update for Business follows the same automatic behavior. Organizations managing deployments through Windows Server Update Services (WSUS) can sync the update by targeting the Windows 11, version 25H2 and Microsoft server operating system 24H2 product under the Security Updates classification. A standalone package is also available from the Microsoft Update Catalog for environments that need to apply it manually.
Prerequisite: .NET Framework 3.5 or 4.8.1 must already be installed on the target machine.
Restart requirement: A restart is required after installation if any files being updated are in use at the time. Microsoft recommends closing all .NET Framework-based applications before applying the update.
Frequently asked questions
Does this update apply to both Windows 11 and Windows Server?
Yes. KB5082417 targets both Windows 11 version 25H2 and Microsoft server operating system 24H2. The same package delivers security and reliability improvements to .NET Framework 3.5 and 4.8.1 on both operating systems, so a single update covers client and server deployments running those versions.
Is a restart always required after installing this update?
Not unconditionally. A restart is required only if files included in the update are in active use when the update is applied. To reduce the chance of a forced restart, Microsoft recommends exiting all .NET Framework-based applications before starting the installation.
Can I deploy this update through WSUS without manual catalog imports?
Yes. WSUS will automatically synchronize KB5082417 provided you configure the correct product scope - Windows 11, version 25H2 and Microsoft server operating system 24H2 - and select the Security Updates classification. No manual catalog import is needed for standard WSUS deployments.
What is the minimum prerequisite for installing this update?
The only stated prerequisite is that .NET Framework 3.5 or 4.8.1 must already be installed on the system. No specific servicing stack update prerequisite is listed for this package on the Microsoft Support page.
