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Date: Thu, 11 Jun 2026 02:44:42 -0700
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Subject: Re: Fwd: BUG?!: Running cygserver switches egid/primary group to
 4095(CurrentSession)
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From: Mark Geisert via Cygwin <cygwin@cygwin.com>
Reply-To: Mark Geisert <mark@maxrnd.com>
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Hello Lionel,

On 6/8/2026 3:35 PM, Lionel Cons via Cygwin wrote:
[...]
> If I run without cygserver id -a returns
> $ id -a
> uid=197620(lcons) gid=197121(Kein)
> groups=197121(Kein),197615(docker-users),545(Benutzer),559(Leistungsprotokollbenutzer),4(INTERAKTIV),66049(KONSOLENANMELDUNG),11(Authentifizierte
> Benutzer),15(Diese Organisation),113(Lokales
> Konto),4095(CurrentSession),66048(LOKAL),262154(NTLM-Authentifizierung),401408(Mittlere
> Verbindlichkeitsstufe)
> 
> but if I start cygserver each new session has gid=4095(CurrentSession)
> as egid/primary group for new terminals
> $ id -a
> uid=197620(lcons) gid=4095(CurrentSession)
> groups=4095(CurrentSession),197121(Kein),197615(docker-users),545(Benutzer),559(Leistungsprotokollbenutzer),4(INTERAKTIV),66049(KONSOLENANMELDUNG),11(Authentifizierte
> Benutzer),15(Diese Organisation),113(Lokales
> Konto),66048(LOKAL),262154(NTLM-Authentifizierung),401408(Mittlere
> Verbindlichkeitsstufe)

I'm unable to reproduce the issue, but I'm a little unsure I have the 
complete list of steps to do so.  Let's start with these questions:

Is your system part of a Windows domain?

How exactly are you starting cygserver?

When you say "each new session" do you mean opening a new Cygwin 
Terminal that presents the usual bash+mintty user CLI?  Or is it some 
other method?

..mark

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