Windows 10 ESU Jan 2026 Update Ditches Old Modem Drivers and Refreshes Secure Boot Certs
The January 2026 Windows 10 ESU release KB5073724 (Build 19045.6809) arrives for ESU subscribers, removing legacy modem drivers (agrsm64.sys/agrsm.sys and smserl64.sys/smserial.sys) which may affect older modems, while adding new Secure Boot certificates and a WinSqlite3.dll security fix. Most users won’t notice changes, but some legacy modems could stop working after the update. The patch bundles security fixes (roughly 112–114 vulnerabilities, including 3 zero-days, with 57 Elevation of Privilege and other categories) and ESU updates run through October 2026. Downloads are via Settings > Windows Update or the Microsoft Update Catalog for Windows 10 Version 22H2 on x64/ARM-64 with ESU,