April 2021 Security Updates


Updates this Month


This release consists of security updates for the following products, features and roles.



  • Azure AD Web Sign-in
  • Azure DevOps
  • Azure Sphere
  • Microsoft Edge (Chromium-based)
  • Microsoft Exchange Server
  • Microsoft Graphics Component
  • Microsoft Internet Messaging API
  • Microsoft NTFS
  • Microsoft Office Excel
  • Microsoft Office Outlook
  • Microsoft Office SharePoint
  • Microsoft Office Word
  • Microsoft Windows Codecs Library
  • Microsoft Windows Speech
  • Open Source Software
  • Role: DNS Server
  • Role: Hyper-V
  • Visual Studio
  • Visual Studio Code
  • Visual Studio Code - GitHub Pull Requests and Issues Extension
  • Visual Studio Code - Kubernetes Tools
  • Visual Studio Code - Maven for Java Extension
  • Windows Application Compatibility Cache
  • Windows AppX Deployment Extensions
  • Windows Console Driver
  • Windows Diagnostic Hub
  • Windows Early Launch Antimalware Driver
  • Windows ELAM
  • Windows Event Tracing
  • Windows Installer
  • Windows Kernel
  • Windows Media Player
  • Windows Network File System
  • Windows Overlay Filter
  • Windows Portmapping
  • Windows Registry
  • Windows Remote Procedure Call Runtime
  • Windows Resource Manager
  • Windows Secure Kernel Mode
  • Windows Services and Controller App
  • Windows SMB Server
  • Windows TCP/IP
  • Windows Win32K
  • Windows WLAN Auto Config Service

Please note the following information regarding the security updates:


Relevant Information

  • Windows 10 updates are cumulative. The monthly security release includes all security fixes for vulnerabilities that affect Windows 10, in addition to non-security updates. The updates are available via the Microsoft Update Catalog. For information on lifecycle and support dates for Windows 10 operating systems, please see Windows Lifecycle Facts Sheet.
  • Microsoft is improving Windows Release Notes. For more information, please see What's next for Windows release notes.
  • A list of the latest servicing stack updates for each operating system can be found in ADV990001. This list will be updated whenever a new servicing stack update is released. It is important to install the latest servicing stack update.
  • In addition to security changes for the vulnerabilities, updates include defense-in-depth updates to help improve security-related features.
  • Customers running Windows 7, Windows Server 2008 R2, or Windows Server 2008 need to purchase the Extended Security Update to continue receiving security updates. See 4522133 for more information.

FAQs, Mitigations, and Workarounds
The following CVEs have FAQs, Mitigations, or Workarounds. You can see these in more detail from the Vulnerabilities tab by selecting FAQs, Mitigations and Workarounds columns in the Edit Columns panel.




Known Issues
You can see these in more detail from the Deployments tab by selecting Known Issues column in the Edit Columns panel.


For more information about Windows Known Issues, please see Windows message center (links to currently-supported versions of Windows are in the left pane).


KB Article Applies To
4504715 SharePoint Server 2019 Language Pack
4504716 SharePoint Server 2019
5001330 Windows 10, Version 2004, Windows Server, Version 2004, Windows 10, Version 20H2, Windows Server, Version 20H2
5001332 Windows Server 2008 (Security-only update)
5001335 Windows 7, Windows Server 2008 R2 (Monthly Rollup)
5001337 Windows 10, Version 1909, Windows Server, Version 1909
5001342 Windows 10, Version 1809, Windows Server 2019
5001347 Windows 10, Version 1607, Windows Server 2016
5001382 Windows 8.1, Windows RT 8.1, Windows Server 2012 R2 (Monthly Rollup)
5001383 Windows Server 2012 (Security-only update)
5001387 Windows Server 2012 (Monthly Rollup)
5001389 Windows Server 2008 (Monthly Rollup)
5001392 Windows 7, Windows Server 2008 R2 (Security-only update)
5001393 Windows 8.1, Windows RT 8.1, Windows Server 2012 R2 (Security-only update)
5001779 Microosft Exchange Server 2019, 2016, 2013


April 2021 Security Updates - Release Notes - Security Update Guide - Microsoft