.NET Framework August 2021 Security and Quality Rollup

Today, we are releasing the August 2021 Security and Quality Rollup Updates for .NET Framework.

Security

This release does not contain any new security fixes. See February 2021 Security and Quality Rollup for the latest security updates.

Quality and Reliability

This release contains the following quality and reliability improvements.

CLR¹

• In scenarios with both high numbers of assemblies and high numbers of GC heaps, Server GC can encounter serious lock contention during generation 2 GCs. A config switch has been introduced as a workaround. It can either be enabled from a .config file:

  <configuration>
    <runtime>
      <GCStaticsNoLock enabled="true"/>
    </runtime>
  </configuration>

  Or by setting environment variable COMPLUS_GCStaticsNoLockto a non-zero value. If the config switch is not enabled then behavior is unchanged compared to previous versions.

Windows Forms

• Addresses an issue where some Windows Forms applications that use ToolStrip controls with ToolStripControlHost, and run under UIA Accessibility Tools, could make Accessibility Tools unresponsive.
• Addresses a regression in the ComboBox item accessible object where Accessibility Tools was not able to distinguish between identical items in the ComboBox and was becoming unresponsive.

¹ Common Language Runtime (CLR)

Getting the Update

The Security and Quality Rollup is available via Windows Update, Windows Server Update Services, and Microsoft Update Catalog.

Microsoft Update Catalog

You can get the update via the Microsoft Update Catalog. For Windows 10, NET Framework 4.8 updates are available via Windows Update, Windows Server Update Services, Microsoft Update Catalog. Updates for other versions of .NET Framework are part of the Windows 10 Monthly Cumulative Update.

**Note**: Customers that rely on Windows Update and Windows Server Update Services will automatically receive the .NET Framework version-specific updates. Advanced system administrators can also take use of the below direct Microsoft Update Catalog download links to .NET Framework-specific updates. Before applying these updates, please ensure that you carefully review the .NET Framework version applicability, to ensure that you only install updates on systems where they apply.

The following table is for Windows 10 and Windows Server 2016+ versions.

The following table is for earlier Windows and Windows Server versions.

Previous Monthly Rollups

The last few .NET Framework Monthly updates are listed below for your convenience:

• .NET Framework July 2021 Cumulative Update Preview
• .NET Framework July 2021 Security and Quality Rollup
• .NET Framework June 2021 Cumulative Update Preview
• .NET Framework June 2021 Security and Quality Rollup Updates