On June 8th, 2021, this update was released to replace a previous update to address a “revocation server was offline” error that may occur during installation. If you've already installed a previous release of this update, no action is required. To obtain the latest version of these updates, see the "How to obtain and install the update" section of the individual update article. Links to each article are found in the "Additional information about this update" section of this article.
On March 9th, 2021, this update was released to replace a previous update to address a "A required certificate is not within its validity period" error that may occur during installation.
Microsoft .NET Framework 3.5.1 Microsoft .NET Framework 4.5.2 Microsoft .NET Framework 4.6 Microsoft .NET Framework 4.6.1 Microsoft .NET Framework 4.6.2 Microsoft .NET Framework 4.7 Microsoft .NET Framework 4.7.1 Microsoft .NET Framework 4.7.2 Microsoft .NET Framework 4.8
IMPORTANT Verify that you have installed the required updates listed in the How to get this update section before installing this update.
IMPORTANT Some customers who use Windows Server 2008 R2 SP1 and have activated their ESU multiple activation key (MAK) add-on before installing the January 14, 2020 updates might need to re-activate their key. Re-activation on the affected devices should only be required once. For information on activation, see this blog post.
IMPORTANT WSUS scan cab files will continue to be available for Windows 7 SP1 and Windows Server 2008 R2 SP1. If you have a subset of devices running these operating systems without ESU, they might show as non-compliant in your patch management and compliance toolsets.
IMPORTANT Customers who have purchased the Extended Security Update (ESU) for on-premises versions of these operating systems must follow the procedures in KB4522133 to continue receiving security updates after extended support ends on January 14, 2020. For more information on ESU and which editions are supported, see KB4497181.
IMPORTANT Starting on January 15, 2020, a full-screen notification will appear that describes the risk of continuing to use Windows 7 Service Pack 1 after it reaches end of support on January 14, 2020. The notification will remain on the screen until you interact with it. This notification will only appear on the following editions of Windows 7 Service Pack 1:
Note The notification will not appear on domain-joined machines or machines in kiosk mode.
Professional. If you have purchased the Extended Security Update (ESU), the notification will not appear. For more information, see How to get Extended Security Updates for eligible Windows devices and Lifecycle FAQ-Extended Security Updates.
IMPORTANT Starting in August, 2019, updates to .NET Framework 4.6 and above, for Windows Server 2008 R2 SP1, and Windows 7SP1, require SHA-2 Code signing support. Please make sure that you have all the latest Windows Updates before applying this update to avoid installation issues. For more detailed information about SHA-2 code signing support updates, please see KB 4474419.
IMPORTANT All updates for .NET Framework 4.7.2, 4.7.1, 4.7, 4.6.2, 4.6.1, and 4.6 require that the d3dcompiler_47.dll update is installed. We recommend that you install the included d3dcompiler_47.dll update before you apply this update. For more information about the d3dcompiler_47.dll, see KB 4019990.
IMPORTANT If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.
An information disclosure vulnerability exists when the .NET Framework improperly handles objects in memory. An attacker who successfully exploited the vulnerability could disclose contents of an affected system's memory. To exploit the vulnerability, an authenticated attacker would need to run a specially crafted application. The update addresses the vulnerability by correcting how the .NET Framework handles objects in memory.
To learn more about the vulnerabilities, go to the following Common Vulnerabilities and Exposures (CVE).
For a list of improvements that were released with this update, please see the article links in the Additional Information section of this article.
Known issues in some parts of this update
This update does not install, and it returns either or both of the following error messages:
This issue was corrected by the latest release of the affected parts in this update.
If you've already installed a previous release of the affected parts, no action is required.
Additional information about this update
The following articles contain additional information about this update as it relates to individual product versions.
4578952 Description of the Security and Quality Rollup for .NET Framework 3.5.1 for Windows 7 SP1 and Windows Server 2008 R2 SP1 (KB4578952)
4578955 Description of the Security and Quality Rollup for .NET Framework 4.5.2 for Windows 7 SP1 and Windows Server 2008 R2 SP1 and Windows Server 2008 SP2 (KB4578955)
4578963 Description of the Security and Quality Rollup for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2 for Windows 7 SP1 and Windows Server 2008 R2 SP1 and Windows Server 2008 SP2 (KB4578963)
4578977 Description of the Security and Quality Rollup for .NET Framework 4.8 for Windows 7 SP1 and Windows Server 2008 R2 SP1 (KB4578977)