It contains a fix for a new version of the Spectre CPU security flaw that was discovered earlier this year alongside a slew of issues with the latest public release of Windows 10. The company also said there will be a battery improvement which is a fix for an issue that could cause “significantly reduced battery life” after installing the April 2018 update.
Improvements and fixes in the update KB4343909 (OS Build 17134.228)
Microsoft listed the following improvements and fixes:
- Provides protection 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.
- 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.
- Security updates to Windows Server.