Description of the security update for SharePoint Enterprise Server 2016: June 8, 2021 (KB5001946)

Summary

This security update resolves a Microsoft SharePoint remote code execution vulnerability, SharePoint spoofing vulnerability, SharePoint Server information disclosure vulnerability, and SharePoint Server remote code execution vulnerability. To learn more about the vulnerabilities, see the following security advisories:

• Microsoft Common Vulnerabilities and Exposures CVE-2021-26420
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31948
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31950
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31963
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31964
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31965
• Microsoft Common Vulnerabilities and Exposures CVE-2021-31966

**Note:**To apply this security update, you must have the release version of Microsoft SharePoint Enterprise Server 2016 installed on the computer.

This public update delivers Feature Pack 2 for SharePoint Server 2016. Feature Pack 2 contains the following feature:

• SharePoint Framework (SPFx)
  This public update also delivers all the features that were included in Feature Pack 1 for SharePoint Server 2016, including:
• Administrative Actions Logging
• MinRole enhancements
• SharePoint Custom Tiles
• Hybrid Taxonomy
• OneDrive API for SharePoint on-premises
• OneDrive for Business modern user experience (available to Software Assurance customers)
  The OneDrive for Business modern user experience requires an active Software Assurance contract at the time that the experience is enabled, either by installation of the public update or by manual enablement. If you don’t have an active Software Assurance contract at the time of enablement, you must turn off the OneDrive for Business modern user experience.For more information, see the following Microsoft Docs articles:
• New features included in the November 2016 Public Update for SharePoint Server 2016 (Feature Pack 1)
• New features included in the September 2017 Public Update for SharePoint Server 2016 (Feature Pack 2)

Improvements and fixes

This update contains security and reliability improvements.This security update also contains fixes and improvements for the following nonsecurity issues in SharePoint Server 2016:

• Improves the performance of certain database operations that are done by the SharePoint Products Configuration Wizard (PSConfig), Timer service jobs, and other features.
• Fixes an issue in which you receive the following error message when you try to clear a filter by using indexed columns in a SharePoint list that has many items:
  Cannot show the value of the filter. The field may not be filterable, or the number of items returned exceeds the list view threshold enforced by the administrator. * Fixes an issue in which Web Parts that depend on**WPProperty don’t work correctly. To enable the Web Parts to work, you have to also follow the steps that are provided in KB 5003528 to declare the affected .NET types to be allowed to accessWPProperty **in the Web.config file.
  This security update also contains a fix for the following nonsecurity issue in Project Server 2016. Consider the following scenario:
• On a task, you set the Status Manager.
• You publish the project.
• Later, while in the same editing session, you change the Status Manager settings.
• You publish the project.
  In this situation, the Status Manager property does not get updated in reporting. Instead of reflecting the new Status Manager, the old one is still observed.

Known issues in this update

• DataFormWebPartmay be blocked from accessing an external URL, and it generates "8scdc"event tags in SharePoint Unified Logging System (ULS) logs. For more information, see KB 5004210.
• When third-party assemblies try to access some sensitive properties, user code might be blocked. When this issue occurs, “8gaol” event entries are logged in SharePoint Unified Logging System (ULS) logs. For example, you may find the following entry in ULS logs:

**8gaol Unable to access this sensitive property : <sensitive property name> from outer assembly.**To fix this issue, install KB5002002 and follow the guidance in KB5004581 to enable trusted third-party assemblies.

How to get and install the update

Method 1: Microsoft Update

This update is available from Microsoft Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to get security updates automatically, see Windows Update: FAQ.

Method 2: Microsoft Update Catalog

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Method 3: Microsoft Download Center

You can get the standalone update package through the Microsoft Download Center. Follow the installation instructions on the download page to install the update.

• Download security update 5001946 for the 64-bit version of SharePoint Enterprise Server 2016

More information

Security update deployment information

For deployment information about this update, see Security update deployment information: June 8, 2021 (KB5004128).

Security update replacement information

This security update replaces previously released security update 5001917.

File hash information

File name		SHA256 hash
sts2016-kb5001946-fullfile-x64-glb.exe		9725FE949F7BCC1BD66DD9E4394DB1AD77061A623BDD0004BBAFBE03481397E8

File information

Download the list of files that are included in security update 5001946.

Information about protection and security

Protect yourself online: Windows Security supportLearn how we guard against cyber threats: Microsoft Security

Change history

The following table summarizes some of the most important changes to this topic.Date	Description
June 29, 2021	Added a known issue in the “Known issues in this update” section.
August 10, 2021	Updated the “Known issues in this update” section to provide a resolution to the issue.