February 9, 2021—KB4601354 (OS Build 17134.2026) - EXPIRED

Highlights

• Corrects historical daylight savings time (DST) information for the Palestinian Authority.

• Updates an issue with German translations of Central European Time.

• Updates for verifying usernames and passwords.

• Updates to improve security when using input devices such as a mouse, keyboard, or pen.

Improvements and fixes

This security update includes quality improvements. Key changes include:

• Updates Internet Explorer’s About dialog to use the standard modern dialog.

• Addresses a possible elevation of privilege vulnerability in the win32k component.

• Corrects historical daylight savings time (DST) information for the Palestinian Authority.

• Addresses an issue with German translations of Central European Time.

• Addresses an issue that causes LSASS.exe to stop working because of a race condition that results in a double free error in Schannel. The exception code is c0000374, and the Event Log displays Schannel event 36888, fatal error code 20, and error state 960. This issue occurs after installing Windows updates from September 2020 and later.

• Security updates to Windows App Platform and Frameworks, Windows Apps, Windows Graphics, Windows Input and Composition, Windows Cloud Infrastructure, Windows Authentication, Windows Fundamentals, Windows Cryptography, and Windows Core Networking.

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 new Security Update Guide website.

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 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 general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB4580398) 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 cumulative update 4601354.