June 12, 2018—KB4284867 (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 support to control use of Indirect Branch Prediction Barrier (IBPB) on some AMD processors (CPUs) for mitigating CVE-2017-5715, Spectre Variant 2 when switching from user context to kernel context. (See AMD Architecture Guidelines for Indirect Branch Control and AMD Security Updates for more details). For Windows client (IT pro) guidance, follow the instructions in KB4073119. For Windows Server guidance, follow the instructions in KB4072698. Use these guidance documents to enable use of IBPB on some AMD processors (CPUs) for mitigating Spectre Variant 2 when switching from user context to kernel context.
• Provides protections from an additional subclass of speculative execution side channel vulnerability known as Speculative Store Bypass (CVE-2018-3639). These protections aren’t enabled by default. For Windows client (IT pro) guidance, follow the instructions in KB4073119. For Windows Server guidance, follow the instructions in KB4072698. Use this guidance document to enable mitigations for Speculative Store Bypass (CVE-2018-3639) in addition to the mitigations that have already been released for Spectre Variant 2 (CVE-2017-5715) and Meltdown (CVE-2017-5754).
• Security updates to Windows apps, Windows Server, Windows storage and filesystems, Windows wireless networking, and Windows virtualization and kernel.
  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 informationFor a list of the files that are provided in this update, download the file information for update 4284867.