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Date: Thu, 25 Feb 2016 10:53:29 +0000
From: John Haxby <>
Subject: Re: CVE Request: bash-completion: dequote command

On 24/02/16 21:58, Kurt Seifried wrote:
> I think in this case it's pretty simply "dequoting should not result in
> code execution" much like the various deserialization flaws (they should
> deserialize the data, not execute random stuff).

My immediate assumption was that an unprivileged user could leave
something lying around that root could complete on.

Within bash-completion, most of the uses of dequote are to find a config
file so there'd be a degree of social engineering to persuade root to
use a config file of your choice.   The other main use seems to be in
_parse_help() and _parse_usage() which parse gnu-style help and
bsd-style usage respectively and that might not need as much social
engineering to exploit.  I didn't investigate further.

Whether or not this turns out to be exploitable at all in
bash-completion, I do agree with Kurt though.


> On Wed, Feb 24, 2016 at 2:56 PM, Fernando Muñoz <>
> wrote:
>> Hello Eric,
>> I never mentioned privilege escalation.
>> This issue how ever could appear when a different application uses
>> user input and calls "dequote" function that not only dequotes, but
>> also executes it as a command. If mitre doesn't consider it CVE worth,
>> that's OK!
>> Regards.
>> On Wed, Feb 24, 2016 at 3:58 PM, Eric Blake <> wrote:
>>> On 02/24/2016 12:08 PM, Fernando Muñoz wrote:
>>>> Marcelo Echeverria and Fernando Muñoz discovered that the dequote
>>>> function included in bash-completion allows to execute arbitrary
>>>> commands since it uses the eval function to call printf and perform
>>>> the actual dequoting. bash-completion is included on Debian, Ubuntu
>>>> OpenSuse [1] and probably other distros.
>>> But what is the privilege escalation?  This is no different than
>>> incorrectly using 'eval' in a shell script - you may have buggy code,
>>> and have an easy-to-trigger bug, but if you can't escalate privileges,
>>> how it is a CVE?
>>> --
>>> Eric Blake   eblake redhat com    +1-919-301-3266
>>> Libvirt virtualization library

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