MICROSOFT has flagged that the Windows 11 cumulative update KB5127648, released on 15 October 2026, can disrupt enterprise Wi-Fi authentication. Reports from network administrators indicate that WPA2-Enterprise, 802.1X, and PEAP authentication fail during the validation handshake, while standard WPA2-Personal networks continue to work.
The issue appears to be linked to recent NTLMv1 security hardening policies, with the problem observed across different hardware—affecting laptops with Intel and Qualcomm wireless adapters—suggesting an operating system-level bug rather than a vendor-specific fault. In testing, removing KB5127648 restores normal wireless connectivity, supporting the assertion that the patch is the root cause.
A temporary registry workaround is described: adjust the BlockNtlmv1SSO setting to permit derived credentials to complete the handshake. The steps involve opening Registry Editor, navigating to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0, creating the DWORD BlockNtlmv1SSO if needed, setting its value to 0, and restarting the PC.
Administrators should weigh the security implications of this change, as it weakens NTLMv1-based hardening, and note that centrally managed environments (via Intune or Group Policy) may overwrite local edits. The article notes that there was no current Microsoft health dashboard entry for this flaw at the time of reporting, and that the workaround is temporary pending an official fix.