Windows 10 KB5066791 marks a significant milestone as it stands as the final update for users who do not opt for the Extended Security Updates (ESU). This month’s release addresses several bugs, primarily benefiting enterprise users, while consumers find themselves with little to no enhancements. The update is being distributed through Windows Update, and Microsoft has made direct download links available for those who prefer manual installation of KB5066791 (.msu).
Upon installation of Windows 10 KB5066791, users may notice a lack of visible changes. When checking for updates, it appears as “2025-10 Cumulative Update for Windows 10 Version 22H2 for x64-based Systems (KB5066791).” Although Microsoft does not explicitly indicate that this is the last update, it subtly encourages users to consider signing up for Extended Security Updates.
Download Links for Windows 10 KB5066791
For those interested in downloading Windows 10 KB5066791, direct links are available through the Microsoft Update Catalog. Users will encounter multiple items, but not all are applicable to every PC. It is advisable to check your OS Edition and CPU architecture by navigating to Settings > System > About. Most users will find their system is 64-bit (x86).
- Select ‘Download’ next to the relevant update package.
- Click on the link to initiate the download of the .msu file for Windows 10 KB5066791.
- Alternatively, you can access the direct link for the 64-bit/22H2 version.
What’s new and broken in Windows 10 Build 19045.6456
In terms of new features or fixes, Windows 10 Build 19045.6456 does not introduce any groundbreaking changes. However, it does rectify some notable issues. According to the release notes, a fix has been implemented for the Chinese Input Method Editor (IME), which previously displayed incorrect characters. Additionally, a bug affecting Windows Remote Management has been resolved, allowing PowerShell Remoting and WinRM to function correctly once again.
Previously, users experienced delays of up to 600 seconds when executing PowerShell commands remotely due to a Windows Update bug, which has now been addressed. The full list of fixes included in Windows 10 KB5066791 is as follows:
- A new servicing stack update has been introduced, potentially facilitating smoother future ESU installations.
- The legacy driver tmdm64.sys, which supported older fax modem hardware, has been removed.
- Windows 10 security has been enhanced with the requirement for Key Storage Provider (KSP) smart card certificates, although this change may lead to issues with smart cards.
Microsoft says Windows 10 KB5066791 causes issues with smart cards
While smart cards are not commonly used by everyday consumers, they play a crucial role in business environments for secure logins and document signing. Unfortunately, Microsoft has confirmed that Windows 10 KB5066791 can lead to smart card failures in certain applications, particularly older 32-bit programs. Users experiencing this issue on Windows 10 Build 19045.6456 may encounter error messages such as “invalid provider type specified” or “CryptAcquireCertificatePrivateKey error.”
Given that this is the last update for Windows 10, it appears unlikely that a fix will be forthcoming unless users enroll in ESU. Microsoft has not indicated any plans to address this issue for the general user base. Instead, users are advised to make adjustments in the Registry by following these steps:
- Open Registry Editor.
- Navigate to HKEYLOCALMACHINESOFTWAREMicrosoftCryptographyCalais.
- Edit the key. Within Calais, check if DisableCapiOverrideForRSA exists.
- If present, double-click DisableCapiOverrideForRSA and set its value to 0.
- If it does not exist, create it and assign a value of 0.
- Reboot Windows.
- Smart Cards should function again.
Microsoft has stated that it is not aware of any other known issues within this release.
When is the first Windows 10 ESU update coming out?
For those opting for Windows 10 ESU, the first security update is scheduled for November 11, 2025. To enroll, users can select the “Enroll now” button on the Windows Update page, link their Microsoft account, and enable OneDrive sync for Settings.
Alternatively, for those who prefer not to use a Microsoft account, a paid option is available through the Windows Store for .99, which grants extended Windows updates until October 13, 2026.
