July 9, 2019—KB4507457 (Security-only update)

**July 19, 2019 - IMPORTANT:**Beginning with the July 2019 updates, Active Directory domain controllers will intentionally block unconstrained delegation across forest, external, and quarantined trusts. Authentication requests for services that use unconstrained delegation over the listed trust types will fail when you request new tickets. Administrators should reconfigure the affected services to use resource-based constrained delegation. For more information, see KB4490425.

Improvements and fixes

This security update includes quality improvements. Key changes include:

• Provides protections against a variant (CVE-2019-1125) of the Spectre Variant 1 speculative execution side channel vulnerability.
• Security updates to Windows Wireless Networking, Windows Server, Windows Storage and Filesystems, Microsoft Graphics Component, Windows Input and Composition, Windows Kernel, and Windows App Platform and Frameworks.
  For more information about the resolved security vulnerabilities, please refer to the Security Update Guide.

Known issues in this update

• Perform the operation from a process that has administrator privilege.
• Perform the operation from a node that doesn’t have CSV ownership.
  Microsoft is working on a resolution and will provide an update in an upcoming release.
  Devices that start up using Preboot Execution Environment (PXE) images from Windows Deployment Services (WDS) or System Center Configuration Manager (SCCM) may fail to start with the error “Status: 0xc0000001, Info: A required device isn’t connected or can’t be accessed” after installing this update on a WDS server.| This issue is resolved in KB4512478.

How to get this update