October 8, 2019—KB4520011 (OS Build 10240.18368)

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Release Date:

Oct 08, 2019

Version:

OS Build 10240.18368

For more information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article.

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Highlights

Updates to improve security when using Internet Explorer and Microsoft Edge.
Updates for verifying user names and passwords.
Updates for storing and managing files.

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Improvements and fixes

This security update includes quality improvements. Key changes include:

Addresses an issue that prevents netdom.exe from displaying the new ticket-granting ticket (TGT) delegation bit for the display or query mode.
Addresses an issue in security bulletin CVE-2019-1318 that may cause client or server computers that don’t support Extended Master Secret (EMS) RFC 7627 to have increased connection latency and CPU utilization. This issue occurs while performing full Transport Layer Security (TLS) handshakes from devices that don’t support EMS, especially on servers. EMS support has been available for all the supported versions of Windows since calendar year 2015 and is being incrementally enforced by the installation of the October 8, 2019 and later monthly updates.
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 Client article. (These registry settings are enabled by default for Windows Client OS editions.)
Addresses an issue with applications and printer drivers that utilize the Windows JavaScript engine (jscript.dll) for processing print jobs.
Security updates to Internet Explorer, Microsoft Edge, Microsoft Scripting Engine, Windows Cryptography, Windows Authentication, Windows Storage and Filesystems, Windows Kernel, and Windows Server.

If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device.

For more information about the resolved security vulnerabilities, please refer to the Security Update Guide.

Windows Update Improvements

Microsoft has released an update directly to the Windows Update client to improve reliability. Any device running Windows 10 configured to receive updates automatically from Windows Update, including Enterprise and Pro editions, will be offered the latest Windows 10 feature update based on device compatibility and Windows Update for Business deferral policy. This doesn't apply to long-term servicing editions.

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Known issues in this update

Symptom

Workaround

Certain operations, such as rename, that you perform on files or folders that are on a Cluster Shared Volume (CSV) may fail with the error, “STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)”. This occurs when you perform the operation on a CSV owner node from a process that doesn’t have administrator privilege.

Do one of the following:

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.

Updates for Windows released October 8, 2019 or later provide protections, tracked by CVE-2019-1318, against an attack that could allow unauthorized access to information or data within TLS connections. This type of attack is known as a man-in-the-middle exploit. Windows might fail to connect to TLS clients and servers that do not support Extended Master Secret for resumption (RFC 7627). Lack of RFC support might cause one or more of the following errors or logged events:

"The request was aborted: Could not create SSL/TLS secure Channel"

SCHANNEL event 36887 is logged in the System event log with the description, "A fatal alert was received from the remote endpoint. The TLS protocol defined fatal alert code is 20."

For information, see KB4528489.

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How to get this update

Before installing this update

Microsoft strongly recommends that you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For more information, see Servicing stack updates.

If you are using Windows Update, the latest SSU (KB4521856) 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

Release Channel	Available	Next Step
Windows Update and Microsoft Update	Yes	None. This update will be downloaded and installed automatically from Windows Update.
Microsoft Update Catalog	Yes	To get the standalone package for this update, go to the Microsoft Update Catalog website.
Windows Server Update Services (WSUS)	Yes	This update will automatically synchronize with WSUS if you configure Products and Classifications as follows: Product: Windows 10 Classification: Security Updates