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Re: CVE Request -- vsftpd -- Do not create network namespace per connection
From: Eugene Teo <eugene () redhat com>
Date: Fri, 29 Jul 2011 16:37:28 +0800

On 06/07/2011 02:28 AM, Josh Bressers wrote:

----- Original Message -----
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] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373
[2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
[3] https://bugzilla.redhat.com/show_bug.cgi?id=711134

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:
[4]
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/31
[5]
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/32

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.

Though not sure, how it would be wrt to CVE identifier(s) assignment.


I'm going to assign CVE-2011-2189 for the kernel. There are numerous
vendors shipping this bug.

I'll leave it up to MITRE if they think vsftpd should get an ID. I don't
think it should myself, but they understand these corner cases better than
I.

Kees, how are you guys fixing this? Disable net_ns and fix vsftpd? I
wonder how other distros approach this. Any suggestions?

Thanks, Eugene


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