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Windows KB5127648 Breaking 802.1X Authentication

Windows KB5127648 Breaking 802.1X Authentication

dariusmp
New Contributor II

Hello Team,

Just to help others: if you started seeing 802.1X authentication problems (Wi‑Fi or Ethernet) after the October Patch Tuesday, check if the affected devices have KB5127648 installed. There are many reports of issues with PEAP‑MSCHAPv2, and in many cases removing the update restores connectivity.

This looks like another step from Microsoft to move away from older technologies based on NTLMv1/MS‑CHAPv2. There is a workaround by changing the Windows registry (BlockNtlmv1SSO=0), but in the long term it probably makes more sense to move to EAP‑TLS instead of continuing to rely on PEAP‑MSCHAPv2.

https://learn.microsoft.com/en-us/answers/questions/6036507/kb5127648-breaks-wpa2-enterprise-802-1x-...

I hope this is helpful to someone.

2 REPLIES 2

sulaxna068debi
New Contributor

Hello, Thanks for sharing! This could save a lot of troubleshooting time. Moving to EAP-TLS seems like the best long-term fix. 

Robert_Haynes
Extreme Employee

Thank you for posting this here.

GTAC has also published its own article below:

Extreme Control - Windows 11 PEAP Authentications Fail After October 2026 Patch Tuesday - KB5127648
https://extreme-networks.my.site.com/ExtrArticleDetail?an=000139510

 

GTM-P2G8KFN