April 12, 2022-KB5012121 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 11
This security update addresses an issue where an unauthenticated attacker could cause a denial of service on an affected system. For more information please see CVE-2022-26832.
Quality and reliability improvements
Winforms - Addresses a leak of IRawElementProviderSimple objects which was introduced in .NET Framework 4.8. This is an opt-in fix, add the following compatibility switch to the app.config file in order to dispose the accessible objects:
<!-- AppContextSwitchOverrides values are in the form of 'key1=true|false;key2=true|false -->
Note: that when the accessibility server application opts into this fix, the accessibility client will receive errors when accessing the disconnected provider. This is expected because the corresponding control window is destroyed. Previous behavior where the provider was returning information for destroyed controls was incorrect.
NET Libraries - Addresses an issue when Ssl negotiation can hang indefinitely when client certificates are used when TLS 1.3 is negotiated. Before the change renegotiation (PostHandshakeAuthentiction) would fail and SslStream or HttpWebRequest would observe a timeout.
Known issues in this updateMicrosoft is not currently aware of any issues in this update.
How to get this updateInstall this update
Release Channel Available Next Step Windows Update and Microsoft Update Yes None. This update will be downloaded and installed automatically from Windows Update. Windows Update for Business Yes None. This update will be downloaded and installed automatically from Windows 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 This update will automatically sync with WSUS if you configure Products and Classifications as follows:
Product: Windows 11
Classification: Security Updates
For a list of the files that are provided in this update, download the file information for cumulative update.
Check Windows Updates
Direct download links for KB5012121 MSU file from Microsoft Update Catalog:
Download KB5012121 MSU for Windows 11 64-bit (x64) - 46.8 MB
Download KB5012121 MSU for Windows 11 ARM64 - 46.8 MB