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Microsoft released KB5004237 and KB5004245 on July 13, 2021, as security updates for different Windows 10 code lines. KB5004237 covers versions 2004, 20H2, and 21H1, including a fix for printing difficulties with some printers. KB5004245 applies to Enterprise-family editions of version 1909. The right package depends on your Windows version and edition, not just the fact that your PC runs Windows 10.
What are KB5004237 and KB5004245?
Both updates were part of Microsoft’s July 2021 “B” security release. KB5004237 is for the Windows 10 2004, 20H2, and 21H1 code line. KB5004245 is for Windows 10 version 1909 Enterprise-family editions: Enterprise, Enterprise and Education, and IoT Enterprise.
| Update | Applicable Windows edition and version | Resulting OS build |
|---|---|---|
| KB5004237 | Windows 10 versions 2004, 20H2, and 21H1 | 19041.1110, 19042.1110, and 19043.1110, respectively |
| KB5004245 | Windows 10 version 1909 Enterprise, Enterprise and Education, and IoT Enterprise | 18363.1679 |
The build number is a useful way to check whether one of these updates is installed. In Windows, open Settings > System > About and look under Windows specifications for the OS build. Builds 19041.1110, 19042.1110, or 19043.1110 correspond to the KB5004237 family; build 18363.1679 corresponds to KB5004245. Confirm your Windows edition and version as well, particularly for version 1909.
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KB5004237 includes security changes and reliability fixes for versions 2004, 20H2, and 21H1. Microsoft highlights improvements to username and password verification and stronger security for basic Windows operations. It also addresses printing problems: Microsoft’s release notes say it “Addresses an issue that might make printing to certain printers difficult.” The problem particularly affected some USB receipt and label printers, across various brands and models.
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The update also enforces Kerberos protections associated with CVE-2020-17049, adds AES protections for CVE-2021-33757, and addresses weak encryption of Primary Refresh Tokens associated with CVE-2021-33779. These are security changes, not separate updates for every listed Windows version.
Microsoft’s KB5004237 notes list other version-specific issues: Japanese Input Method Editor (IME) may produce incorrect Furigana characters; custom offline media may remove Edge Legacy without automatically replacing it; some devices may encounter PSFX_E_MATCHING_BINARY_MISSING after earlier updates; and some provisioned UWP apps may fail to open after a device reset. The notes identify later fixes or workarounds for these issues. Check the Microsoft KB5004237 release notes for the relevant resolution before troubleshooting a particular device.
What does KB5004245 fix?
KB5004245 adds AES encryption protections for CVE-2021-33757. Microsoft also lists security updates across Windows components, including authentication, User Account Control (UAC), the kernel, virtualization, Windows Subsystem for Linux, MSHTML, scripting, and graphics. It is the version 1909 Enterprise-family package; it is not the matching update for Windows 10 Home or Pro version 1909.
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USB receipt and label printer problems
KB5004237 addresses printing difficulties affecting certain printers, especially some USB receipt and label printers. That fix does not mean every printer problem is resolved, nor does the release note identify every affected model. If printing trouble began after an update, verify the Windows version and build first, then consult Microsoft’s notes for the update installed on that device.
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Smart-card authentication on domain-connected systems
A separate known issue can cause printers, scanners, or multifunction devices to fail when smart-card (PIV) authentication is used after the July 13 updates are installed on domain controllers. Microsoft says affected devices do not comply with section 3.2.1 of RFC 4556 and directs administrators to KB5005408 for details. This issue is distinct from the USB printer difficulties addressed by KB5004237.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do you choose the correct update?
- Open Settings > System > About and note the Windows version, edition, and OS build.
- For versions 2004, 20H2, or 21H1, check whether the device is on the KB5004237 code line. Its corresponding builds are 19041.1110, 19042.1110, and 19043.1110.
- For version 1909, check the edition. KB5004245 is for Enterprise, Enterprise and Education, and IoT Enterprise editions, and produces build 18363.1679.
- Use Windows Update and the applicable Microsoft release notes to check installation status and any relevant prerequisites or known issues.
Version 1909’s availability depended on edition: Home, Pro, Pro for Workstation, Nano Container, and Server SAC reached end of service on May 11, 2021, while Enterprise, Education, and IoT Enterprise continued receiving updates at that point. An edition that had reached end of service should not be treated as eligible for the 1909 Enterprise-family package.
What prerequisites and download options apply?
Servicing-stack prerequisites vary by package and installation scenario. KB5004237 lists prerequisites including KB5003173 for WSUS scenarios and additional requirements for offline images. KB5004245 requires the April 13, 2021 servicing stack update KB5001406 or the newer KB5004748; IoT Enterprise specifically requires KB5004748. Check the applicable Microsoft notes before deploying through WSUS or servicing an offline image.
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Quick Recap
- Microsoft KB5004237 release notes
- Microsoft KB5004245 release notes
- Microsoft Windows release history
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