January 2026 Extended Security Update (ESU) KB5073724 for Windows 10: Removal of Legacy Modem Drivers

The release of Windows 10 KB5073724 is now available, albeit exclusively for those enrolled in the Extended Security Updates (ESU) program. By subscribing to ESU for Windows 10, users can receive critical security updates until October 2026; however, it’s essential to note that this does not introduce any significant new features, as official support for Windows 10 has officially concluded.

This latest update, titled 2026-01 Cumulative Update for Windows 10 Version 22H2 for x64-based Systems (KB5073724), was installed on my machine running Windows 10 ESU, resulting in the system being upgraded to Build 19045.6809.

To download and install the update, navigate to Settings > Updates & Security > Windows Update or alternatively, access the Update Catalog.

Direct Download Links for Windows 10 KB5073724

For those looking for direct downloads, here are the links for 64-bit and ARM-64 installers. Keep in mind that these can malfunction if you are not a subscriber to ESU.

Key Changes in Windows 10 Build 19045.6809

According to the official release notes, Microsoft has removed certain modem drivers essential for internet connectivity on older systems. Thankfully, the impact on users is expected to be minimal, with an estimated 99.99% of users remaining unaffected.

The following drivers have been eliminated from Windows 10:

agrsm64.sys (x64)
agrsm.sys (x86)
smserl64.sys (x64)
smserial.sys (x86)

Microsoft cautions that any modem devices that rely on these drivers may no longer function correctly after installing the KB5073724 update. However, I tested my modem on several older PCs post-update, and it continued to operate without issues.

Additionally, the January 2026 update incorporates new Secure Boot certificates, replacing some that recently expired. For clarity, Secure Boot certificates are critical as they are embedded in a PC’s UEFI firmware and verify whether the Windows boot loader can execute during startup. Many older systems still utilize Microsoft certificates issued in 2011, which have now expired, necessitating updates to maintain security. Replacing these certificates ensures continued trust in new boot components, thus protecting against vulnerabilities.

This update is particularly vital for enterprises employing Windows 10, as they need to address Secure Boot certificates without requiring active intervention from consumers when Windows Update is enabled.

Furthermore, Microsoft has updated a pivotal component known as WinSqlite3.dll with necessary security fixes. This adjustment follows reports where some antivirus software flagged applications utilizing WinSqlite3.dll as potential vulnerabilities. If you encounter security alerts, Microsoft advises updating all applications from the Windows Store.

For third-party applications utilizing sqlite3.dll that are flagged as vulnerable, it is advisable to contact the respective application developers. Additionally, if a Microsoft application is identified as vulnerable, users should access the Windows Store to apply any updates.

As of now, Microsoft has not reported any significant issues linked to the Windows 10 KB5073724 update.

Source & Images