Microsoft Releases Windows 10 1803 Update KB4343909 for Patch Tuesday

It’s Patch Tuesday for August and Microsoft is rolling out new cumulative updates for all currently supported versions of Windows and Server.

It’s Patch Tuesday and Microsoft today is rolling out cumulative update KB4343909 for Windows 10 1803 April Update. There are no new features to report but it does include security patches and other system improvements. It will also bump your build number to 17134.228. The company is also rolling out cumulative updates and patches for all other supported versions of Windows and Server.

Windows 10 Cumulative Update KB4343909

  • Provides protections against a new speculative execution side-channel vulnerability known as L1 Terminal Fault (L1TF) that affects Intel® Core® processors and Intel® Xeon® processors (CVE-2018-3620 and CVE-2018-3646). Make sure previous OS protections against Spectre Variant 2 and Meltdown vulnerabilities are enabled using the registry settings outlined in the Windows Client and Windows Server guidance KB articles. (These registry settings are enabled by default for Windows Client OS editions, but disabled by default for Windows Server OS editions.)
  • Addresses an issue that causes high CPU usage that results in performance degradation on some systems with Family 15h and 16h AMD processors. This issue occurs after installing the June 2018 or July 2018 Windows updates from Microsoft and the AMD microcode updates that address Spectre Variant 2 (CVE-2017-5715 – Branch Target Injection).
  • Addresses an issue that prevents apps from receiving mesh updates after resuming. This issue occurs for apps that use Spatial Mapping mesh data and participate in the Sleep or Resume cycle.
  • Ensures that Internet Explorer and Microsoft Edge support the preload=”none” tag.
  • Addresses an issue that prevents some applications running on HoloLens, such as Remote Assistance, from authenticating after upgrading from Windows 10, version 1607, to Windows 10, version 1803.
  • Addresses an issue that significantly reduced battery life after upgrading to Windows 10, version 1803.
  • Addresses an issue that causes Device Guard to block some ieframe.dll class IDs after installing the May 2018 Cumulative Update.
  • Addresses a vulnerability related to the Export-Modulemember() function when used with a wildcard (*) and a dot-sourcing script. After installing this update, existing modules on devices that have Device Guard enabled will intentionally fail. The exception error is “This module uses the dot-source operator while exporting functions using wildcard characters, and this is disallowed when the system is under application verification enforcement.” For more information, see and
  • Addresses an issue that was introduced in the July 2018 .NET Framework update. Applications that rely on COM components were failing to load or run correctly because of “access denied,” “class not registered,” or “internal failure occurred for unknown reasons” errors.

You should get this update automatically over the next couple of days, or, if you want to stay on top of things, head to Settings > Update & security > Windows update to get it. Or, manually download KB4343909 here. After restarting your system, hit the Windows key and type: winver, and hit Enter. You will see your version has been bumped to Build 17134.228.

Since it’s Patch Tuesday, there are also new cumulative updates for other Windows 10 versions including KB4343897 for Fall Creators Update 1709 and KB4343885 for Creators Update 1703. Of course, you’ll want to check Windows Update for new patches that were released today on any other supported version of Windows or Server.

1 Comment

1 Comment

  1. Jeffrey Frankel

    I have Windows 10 and allowed the Patch this Tuesday to update my computer. Wednesday morning when I booted up I was horrified to find my clock was wrong. I have never had a clock problem on this or other computers. I had to manually adjust the clock. It was bad, because I generally rely on the clock in the bottom right hand corner to tell me the time. After a half hour of working on the computer I looked at my phone and was horrified to find that the windows clock was half hour slow.
    In addition I find that when I type some letters, I, i, l, and c they are duplicated on the screen in my mailbird, and comments section of web pages I don’t know what the recipient sees.

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