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Date: Mon, 6 Jun 2011 10:14:13 -0700
From: Chris Evans <>
To: oss-security <>
Cc: "Steven M. Christey" <>, Greg KH <>, Kees Cook <>
Subject: Re: CVE Request -- vsftpd -- Do not create network namespace per connection

On Mon, Jun 6, 2011 at 9:19 AM, Jan Lieskovsky <> wrote:

> Hello, Josh, Steve, vendors,
>  It was found that vsftpd, Very Secure FTP daemon, when the network
> namespace (CONFIG_NET_NS) support was activated in the kernel, used to
> create a new network namespace per connection. A remote attacker could
> use this flaw to cause a memory pressure and denial of the vsftpd
> service.
> References:
> [1]
> [2]
> [3]
> This one being a bit tricky one -- from my understanding of the issue,
> vsftpd doesn't necessarily have a security flaw on its side. It's
> kernel issue / bug, which allows this to be used for vsftpd DoS:

Yes, I will be considering this a kernel issue.
vsftpd also uses one (or more!) process per connection. I'd have though that
a process structure plus stack etc. would be a lot more heavyweight than an
empty network namespace, but obviously not :)

> [5]
> Short-term solution would be probably to address this on the vsftpd
> side, the long-term one then being to get this fixed in kernel.

It's actually configurable in vsftpd.conf:

So for a short term fix, all you need is to deploy that config change.
Looking at the Changelog, network isolation was added in vsftpd-2.2.0, and
the config setting has been there from v2.2.0 as well.


> Though not sure, how it would be wrt to CVE identifier(s) assignment.
> Steve, could you advice here?
> Thank you & Regards, Jan.
> --
> Jan iankko Lieskovsky / Red Hat Security Response Team

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