Windows 10 KB5122878 Released With September 2026 Security Updates
Microsoft has released Windows 10 KB5122878, the September 2026 Extended Security Update (ESU). The cumulative update includes security fixes from the record-breaking September 2026 Patch Tuesday, along with several bug fixes and improvements for supported Windows 10 devices.
Windows 10 Enterprise LTSC customers and users enrolled in the Windows 10 ESU program can install KB5122878 through Windows Update. Open Settings, go to Windows Update, and select Check for updates to download and install the update manually.
Source: BleepingComputer
After installing Windows 10 KB5122878, standard Windows 10 systems will be updated to build 19045.7725. Windows 10 Enterprise LTSC 2021 devices will receive build 19044.7725.
What’s new in Windows 10 KB5122878?
Microsoft is no longer adding new features to Windows 10. As a result, KB5122878 primarily delivers security updates, reliability improvements, and bug fixes for Windows 10 versions 21H2 and 22H2, as well as supported Enterprise LTSC editions.
The update also includes fixes released as part of the September 2026 Patch Tuesday security update. Microsoft addressed 966 vulnerabilities across its products, including two zero-day flaws that were actively exploited in the wild.
According to Microsoft’s KB5122878 support page, the Windows 10 update includes the following changes:
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[Secure Boot] This update adds more reliable device-targeting data and expands the number of devices that can automatically receive new Secure Boot certificates. Microsoft will continue deploying the certificates through Windows Update to supported PCs and unmanaged business devices in the coming months.
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[Date and time] The update adjusts Moroccan Standard Time to reflect Morocco’s permanent transition to UTC+00:00, which takes effect on September 20, 2026. This ensures that Windows displays the correct local time after the change.
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[OMA DM protocol] KB5122878 improves logging for the OMA DM Client (
omadmclient.exe). Additional debugging information is now recorded when the client connects to a server. -
[Windows Code Integrity policies] Microsoft has improved application compatibility during the Windows Certificate Authority rotation. Windows now recognizes Microsoft Windows Production PCA 2026 RSA2048-SHA256 as equivalent to PCA 2011.
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[Remote Desktop] This update resolves an issue affecting Remote Desktop audio redirection. Under certain configurations, audio from a remote session may not play on the local computer.
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[BitLocker Group Policy] Microsoft has addressed a known issue in which devices with non-recommended BitLocker Group Policy settings may require users to enter a BitLocker recovery key.
Microsoft currently reports that Windows 10 KB5122878 has no known issues.
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Source: www.bleepingcomputer.com