Ubuntu Trusty can't update bash

Question

I'm trying to upgrade bash to the latest version to fix the bash vulnerability, but my machine can't seem to find the new package to install. Don't know what I'm doing wrong.

user@machine:~$ env VAR='() { :;}; echo Bash is vulnerable!' bash -c "echo Bash Test"
Bash is vulnerable!
Bash Test
user@machine:~$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
user@machine:~$ apt-cache policy bash
bash:
  Installed: 4.3-6ubuntu1
  Candidate: 4.3-6ubuntu1
  Version table:
 *** 4.3-6ubuntu1 0
        500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status
user@machine:~$ sudo apt-get install bash=4.3-7ubuntu1.3 
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Version â4.3-7ubuntu1.3â for âbashâ was not found

/etc/apt/sources.list:

# deb cdrom:[Ubuntu 9.10 _Karmic Koala_ - Release amd64 (20091027)]/ karmic main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://gb.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty main restricted

## Major bug fix updates produced after the final release of the
## distribution.

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://gb.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://gb.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://gb.archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse
# deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu karmic partner
# deb-src http://archive.canonical.com/ubuntu karmic partner

deb http://extras.ubuntu.com/ubuntu trusty main #Third party developers repository

Answer 1

Something was wrong with the sources in /etc/apt/sources.list. Replacing them with the sample list from http://ubuntuguide.org/wiki/Ubuntu_Trusty_Packages_and_Repositories and updating again fixed the issue.

Answer 2

You might need to update package metadata. Run apt-get update && apt-get upgrade. That should install all currently available security updates.