Microsoft has just released new “Patch Tuesday” updates for all supported versions of Windows 10, if you’re running the April 2018 update then you should be seeing the build 17134.228 (KB4343909) in Windows Update. This new build brings a fix for a new variant of the Spectre CPU security flaw that was discovered earlier this year, and Microsoft says that it also address an issue where previous Spectre fixes could cause hight CPU usages on PCs with certain AMD processors.
The release notes also mention a fix for an issue that could cause “significantly reduced battery life” after installing the April 2018 update, something that laptops and tablets users will likely appreciate. The full list of fixes is available below:
- 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 https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8200 and https://aka.ms/PSModuleFunctionExport.
- Security updates to Windows Server.
There is still one known issue with this new Windows 10 build, which was already present in the last two cumulative updates: Applications that rely on .NET Framework can fail to start after installing the July 2018 .NET Framework Security updates, and Microsoft is once again saying that it will provide a fix in an upcoming update. In the meantime, let us know in the comments if you encounter any issues after installing this new build.
Further reading: cumulative updates, Patch Tuesday, Windows 10, Windows 10 April 2018 Update
