samba - Sep 2025 - Smart card (PKINIT) logon under Windows 11 with Credential Guard

> I?m testing smart card (PKINIT) logon under Windows 11 with Credential
> Guard enabled.
> 
>   -  When the client talks to a *Windows Server AD*, logon succeeds.
>   -  When the client talks to a *Samba AD (Heimdal)*, logon fails
immediately
>   with the error:
> 
>   *"A null reference pointer was passed to the stub"*
>   shown on the Windows logon screen.
Yes, I?m seeing exactly this behavior, and I know of at least one other org that
is as well.  I?m running vanilla Samba 4.22.1 and I remember seeing this with an
older version too, so it?s not a recent change.  Would love to find a solution,
other than disabling Credential Guard.

_Rob