Microsoft has rolled out the latest monthly security update for Windows 10, designated as KB5120249. This patch is part of the Extended Security Updates (ESU) program, meaning it focuses strictly on security patches and reliability fixes rather than introducing new features. It is currently available for Windows 10 versions 22H2 and 21H2, as well as Windows 10 Enterprise LTSC 2021 and Windows 10 IoT Enterprise LTSC 2021.
While the primary goal of this release is to close known security vulnerabilities, the changelog highlights two notable improvements that address long-standing user complaints and ongoing hardware compatibility efforts. If you are running Windows 10 under the ESU agreement, this update is essential for maintaining both system security and peripheral functionality.
#1 Secure Boot Certificate Coverage Expansion
One of the most significant aspects of KB5120249 is its continued effort to resolve the outdated Secure Boot certificate issue. Microsoft confirmed via the Windows Insider Blog that this update includes additional high-confidence device targeting data. This data increase means a broader range of devices will now be eligible to automatically receive new Secure Boot certificates through Windows Update.
For years, certain PCs have faced boot failures or security warnings because their firmware relied on expired Microsoft UEFI CA certificates. By expanding the device targeting data, Microsoft is effectively widening the net of supported hardware. This ensures that both standard consumer PCs and non-managed business devices can automatically pull the necessary certificate updates without requiring manual intervention from IT administrators.
This deployment strategy aligns with Microsoft’s broader push to enforce modern security standards across the Windows ecosystem. As Secure Boot becomes a baseline requirement for modern operating systems and hardware compatibility, keeping these certificates current is critical for preventing boot loops and maintaining trust chain integrity.
#2 File History Backup Errors Resolved
Another practical fix in this patch addresses a frustrating issue with File History. Users who rely on automatic backups to network shares via Server Message Block (SMB) have reported encountering an incorrect “invalid credentials” error. When this bug triggers, scheduled backups simply fail to copy any files, leaving your data unprotected without obvious warning signs.
According to the release notes, KB5120249 resolves this credential validation glitch. In practice, this means that automated backup jobs targeting SMB network locations should now authenticate correctly and resume normal operations. For users who depend on File History for versioning and disaster recovery, this fix restores confidence in the reliability of network-attached storage backups.
#3 Defender and Framework Updates
Beyond the headline fixes, this update also refreshes several core system components. Microsoft Defender Antivirus receives its latest signature updates to combat emerging threats. Additionally, the .NET Framework and the Windows Malicious Software Removal Tool (MSRT) are updated to their latest versions. These background updates ensure that your system’s defensive layers remain synchronized with the latest threat intelligence.
What This Means for You
If you are enrolled in the Extended Security Updates program, this patch is mandatory for maintaining a secure and stable environment. The Secure Boot improvements reduce the risk of firmware-related boot failures, while the File History fix prevents silent backup losses. Without this update, devices may continue to experience credential errors during network backups or miss out on automatic certificate deployments.
How to Get It
Windows 10 will install KB5120249 automatically once it becomes available through Windows Update. The process typically takes only a few minutes. If you prefer manual control, you can download the update directly from the Microsoft Update Catalog, where the total download size is just under 1 GB. Remember, your device will only receive this update if it is properly enrolled in the ESU program, which guarantees security support until at least October 2027.
Source: PCWorld
Build details:
- kb5120249
Over to you: Are you relying on the Extended Security Updates program for your Windows 10 devices, or have you already migrated to a newer OS?
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