The Final Hang-Up: Microsoft Disables Legacy Modem Drivers for Security

According to Microsoft, a number of legacy modem drivers have been decommissioned after users installed the latest Windows 11 cumulative updates, with the result that some hardware‑built integrated modems can no longer access the internet.

The article notes that AGRSM64.SYS and AGRSM.SYS (developed by Agere Systems) and SMSERL64.SYS and SMSERIAL.SYS (associated with Motorola and third‑party soft‑modems) were targeted for neutralisation due to security flaws identified in 2023 and 2025, including CVE-2023-31096 and CVE-2025-24052. It emphasises that the latter vulnerability is a stack‑based buffer overflow that could allow a malicious actor to launch an attack even if the modem hardware is not in use.

Microsoft has prioritised systemic integrity by disabling these drivers within Windows 11, a move that predominantly affects specialised sectors and industrial control environments, with no official remediation currently available. Users are left with the choice of uninstalling the security patches or forfeiting future system updates.