KB5034122: Cumulative update for Windows 10, versions 21H2 and 22H2, January 2024. Critical Kerberos and Hyper-V flaws patched; Copilot issues remain

The update fixes 34 vulnerabilities, including critical flaws in Kerberos and Hyper-V. It is no longer available through Microsoft release channels as of March 31, 2026.

Does it affect you? Applies to: This update applies to Windows 10 version 22H2 and to Windows 10 version 21H2 Enterprise, Education, IoT Enterprise, and Enterprise multi-session editions.

What changes

Fixes 3 changes

ActiveX scroll bar

For: Windows 10 version 21H2 devices using IE mode

The ActiveX scroll bar works in IE mode again.¹
Applies to Windows 10 version 21H2 Enterprise, Education, IoT Enterprise, and Enterprise multi-session editions.

Smart card authentication

For: Windows 10 version 21H2 devices using smart card authentication on a remote system

The device no longer shuts down after 60 seconds when a smart card is used to authenticate on a remote system.²
Applies to Windows 10 version 21H2 Enterprise, Education, IoT Enterprise, and Enterprise multi-session editions.

Smart card sign-in

For: Windows 10 version 21H2 devices using smart cards with multiple certificates

The smart card icon appears at sign-in when the card has multiple certificates.³
Applies to Windows 10 version 21H2 Enterprise, Education, IoT Enterprise, and Enterprise multi-session editions.

Improvements 2 changes

Windows 10, version 22H2

For: Windows 10 version 22H2 devices

This build includes all the improvements from supported Windows 10 version 21H2 editions.⁴

Servicing stack

For: Windows 10 devices

The component that installs Windows updates receives quality improvements to help devices receive and install Microsoft updates reliably.⁵
The servicing stack update covers OS builds 19044.3745 and 19045.3745.

Known issues

Open Affects: Everyone

Windows devices using more than one (1) monitor might experience issues with desktop icons moving unexpectedly between monitors or other icon alignment issues when attempting to use Copilot in Window…

On devices with more than one monitor, desktop icons might move unexpectedly between monitors or have other alignment issues when you use Copilot in Windows preview.⁶

How to apply the workaround Workaround

The new Copilot experience, gradually rolling out to devices with KB5039299 or later, is expected to address this issue.⁶
Open Affects: Everyone

Copilot in Windows (in preview) is not currently supported when your taskbar is located vertically on the right or left of your screen.

Copilot in Windows preview is not supported when the taskbar is vertical on the right or left side of the screen.⁶

How to apply the workaround Workaround

The new Copilot experience, gradually rolling out to devices with KB5039299 or later, is expected to address this issue.⁶
Resolved Affects: Organizations and IT administrators Resolved by KB5034203

Using the FixedDrivesEncryptionType or [SystemDrivesEncryptionType](https://nam06.safelinks.protec…

In some MDM environments, the BitLocker “Require Device Encryption” status might incorrectly show error 65000 when the specified drive-encryption policies are enabled and set to full encryption or used space only. KB5034203 addresses this reporting issue; drive encryption and reporting of other issues are not affected.⁷

Resolution Fixed in KB5034203

Install KB5034203 (or a later cumulative update) on affected devices. No manual workaround is required after updating.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released: 2024-01-09
Type: Cumulative update

Version	Build	Channel
21H2	19044.3930	General availability
22H2	19045.3930	General availability

Security

34 vulnerabilities fixed

2 critical 32 important

Vulnerability	Severity	CVSS
CVE-2024-20674 Windows Kerberos Security Feature Bypass Vulnerability	Critical	8.8
CVE-2024-20700 Windows Hyper-V Remote Code Execution Vulnerability	Critical	7.5

The table lists the 2 exploited, publicly disclosed or critical vulnerabilities. See all 34 vulnerabilities →

Sources

Microsoft Support: KB5034122

Updated Oct 27, 2026

Cited passages from Microsoft's official notes (7)

1. This update addresses an issue that affects the ActiveX scroll bar. It does not work in IE mode. support.microsoft.com
2. This update addresses an issue that causes your device to shut down after 60 seconds. This occurs when you use a smart card to authenticate on a remote system. support.microsoft.com
3. This update addresses an issue that affects the display of a smart card icon. The icon does not appear when you sign in. This occurs when there are multiple certificates on the smart card. support.microsoft.com
4. This build includes all the improvements from the supported Windows 10, version 21H2 editions. support.microsoft.com
5. This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. support.microsoft.com
6. We are gradually rolling out a new Copilot experience for devices with KB5039299 or later updates installed. support.microsoft.com
7. This issue is addressed in KB5034203. support.microsoft.com

Checked automatically: 8 of 8 checks passed, 7 quoted passages · compared with Microsoft's page on Nov 8, 2026

Quotes found in the official pages: passed
Numbers found in the sources: passed
Vulnerabilities from the dossier only: passed
Links to allowed domains only: passed
Every official change covered: passed
Readable plain text: passed
Changes confirmed by the file list: passed
Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 5/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake