Microsoft January Patch Tuesday Security Updates for Windows 10/11
Microsoft shipped its January Patch Tuesday security updates for Windows 10 (including ESU/LTSC) and Windows 11, addressing a large set of vulnerabilities and rolling in additional platform hardening changes. Windows 10’s KB5073724 (ESU) updates systems to build 19045.6809 (and LTSC 2021 to 19044.6809) and includes security/bug fixes plus a phased update to handle expiring Secure Boot certificates; it also removes legacy Agere modem drivers (agrsm64.sys, agrsm.sys, smserl64.sys, smserial.sys), which can break dependent modem hardware. Windows 11 cumulative updates KB5074109 (25H2/24H2) and KB5073455 (23H2) are mandatory and include fixes for issues such as WSL mirrored networking failures (“No route to host”) impacting VPN access and RemoteApp connection failures in Azure Virtual Desktop environments.
Third-party analysis of the same Patch Tuesday release reported 112 vulnerabilities (with 8 marked critical) and at least one vulnerability observed exploited in the wild: CVE-2026-20805. The critical issues highlighted include multiple remote code execution vulnerabilities across Windows components and Office applications (including LSASS, Word, Excel, and Office), plus elevation of privilege flaws such as CVE-2026-20822 (Windows Graphics Component, use-after-free leading to potential SYSTEM privileges) and CVE-2026-20854 (LSASS RCE over the network without requiring elevated privileges). Organizations should prioritize rapid deployment of the January Windows updates, with particular attention to exploited-in-the-wild items and critical RCE/EoP paths.
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