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Date: Fri, 18 Dec 2015 08:54:53 +0000
From: Fiedler Roman <>
To: "" <>
Subject: AW: CVE Request: Linux kernel: privilege escalation
 in user namespaces


> Von: John Johansen []
> Betreff: [oss-security] CVE Request: Linux kernel: privilege escalation in 
> user
> namespaces
> Hi,
> I haven't seen CVE request for this one yet so,
> Jann Horn reported a privilege escalation in user namespaces to the lkml
> mailing list
> if a root-owned process wants to enter a user namespace for some reason
> without knowing who owns it and therefore can't change to the namespace
> owner's uid and gid before entering, as soon as it has entered the
> namespace, the namespace owner can attach to it via ptrace and thereby
> gain access to its uid and gid.

Could it be, that this is identical to

which led to

except, that combined with another timerace, this gives host uid 0 escalation 
no matter how the target namespace looks like or target uid is known or not?

The bug is marked as fixed, but looking at it, the very similar kernel issue 
seems not be addressed and it is also still marked "private security" although 
fix was released.

I could ask Ubuntu Security if we should make that bug public or perhaps could 
add accounts to the list of authorized users when told the Launchpad user name 
to add.

Kind Regards,

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