Microsoft will eliminate default trust for kernel drivers signed through the outdated cross-signed root program with the April 2026 Windows update. All new kernel drivers must be certified via the Windows Hardware Compatibility Program (WHCP). This change will affect Windows 11 builds 24H2, 25H2, and 26H1, as well as Windows Server 2025, with future versions following the same standards. The update will begin in evaluation mode, monitoring driver loads for compliance before transitioning to enforcement mode. An allow list of reputable drivers will be maintained for legacy hardware, and enterprises can use Application Control for Business policies to authorize specific drivers. Users with older hardware may face compatibility issues if their drivers are not WHCP-certified.