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Ubuntu Security Notice USN-3294-1
May 17, 2017

bash vulnerabilities
===========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.04
- Ubuntu 16.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in Bash.

Software Description:
- bash: GNU Bourne Again SHell

Details:

Bernd Dietzel discovered that Bash incorrectly expanded the hostname when
displaying the prompt. If a remote attacker were able to modify a hostname,
this flaw could be exploited to execute arbitrary code. This issue only
affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10.
(CVE-2016-0634)

It was discovered that Bash incorrectly handled the SHELLOPTS and PS4
environment variables. A local attacker could use this issue to execute
arbitrary code with root privileges. This issue only affected Ubuntu 14.04
LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2016-7543)

It was discovered that Bash incorrectly handled the popd command. A remote
attacker could possibly use this issue to bypass restricted shells.
(CVE-2016-9401)

It was discovered that Bash incorrectly handled path autocompletion. A
local attacker could possibly use this issue to execute arbitrary code.
This issue only affected Ubuntu 17.04. (CVE-2017-5932)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.04:
  bash                            4.4-2ubuntu1.1

Ubuntu 16.10:
  bash                            4.3-15ubuntu1.1

Ubuntu 16.04 LTS:
  bash                            4.3-14ubuntu1.2

Ubuntu 14.04 LTS:
  bash                            4.3-7ubuntu1.7

In general, a standard system update will make all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-3294-1
  CVE-2016-0634, CVE-2016-7543, CVE-2016-9401, CVE-2017-5932

Package Information:
  https://launchpad.net/ubuntu/+source/bash/4.4-2ubuntu1.1
  https://launchpad.net/ubuntu/+source/bash/4.3-15ubuntu1.1
  https://launchpad.net/ubuntu/+source/bash/4.3-14ubuntu1.2
  https://launchpad.net/ubuntu/+source/bash/4.3-7ubuntu1.7