August 14, 2018—KB4343899 (Security-only update)

Improvements and fixes

This security update includes quality improvements. No new operating system features are being introduced in this update. Key changes include:

• 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).

• Provides protections against an additional vulnerability involving side-channel speculative execution known as Lazy Floating Point (FP) State Restore (CVE-2018-3665) for 32-Bit (x86) versions of Windows.

For more information about the resolved security vulnerabilities, see the Security Update Guide.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

This update is now available for installation through WSUS. To get the standalone package for this update, go to the Microsoft Update Catalog website.

File information

For a list of the files that are provided in this update, download the file information for update 4343899.