Windows 10 ESU Jan 2026 Update Ditches Old Modem Drivers and Refreshes Secure Boot Certs

TL;DR
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,
- Windows 10 KB5073724 is January 2026's Extended Security Update (ESU) and it removes old modem drivers Windows Latest
- Patch Tuesday, January 2026 Edition Krebs on Security
- Microsoft Patch Tuesday addresses 112 defects, including one actively exploited zero-day CyberScoop
- Microsoft Fixes 114 Windows Flaws in January 2026 Patch, One Actively Exploited The Hacker News
- The January 2026 Security Update Review Zero Day Initiative
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