USN-3294-1: Bash vulnerabilities

17 May 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

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

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

References