September 10, 2019—KB4516051 (Security-only update)

Improvements and fixes

This security update includes quality improvements. Key changes include:

• Provides protections against a new subclass of speculative execution side-channel vulnerabilities, known as Microarchitectural Data Sampling, for 32-Bit (x86) versions of Windows (CVE-2019-11091, CVE-2018-12126, CVE-2018-12127, CVE-2018-12130). Use the registry settings as described in the Windows Server article. (These registry settings are enabled by default for Windows Server OS editions.)

• Security updates to Windows App Platform and Frameworks, Windows Kernel, Windows Input and Composition, Windows Media, Windows Authentication, Windows Datacenter Networking, Windows Storage and Filesystems, the Microsoft JET Database Engine, and Windows Server .

For more information about the resolved security vulnerabilities, please refer to 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

Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest Rollup. SSUs improve the reliability of the update process to mitigate potential issues while installing the Rollup and applying Microsoft security fixes. 

If you are using Windows Update, the latest SSU (KB4517134) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog. 

Install this update

File information

For a list of the files that are provided in this update, download the file information for update 4516051.