The following updates has been released for Ubuntu Linux:

USN-3608-1: Zsh vulnerabilities
USN-3609-1: Firefox vulnerability

USN-3608-1: Zsh vulnerabilities

==========================================================================
Ubuntu Security Notice USN-3608-1
March 27, 2018

zsh vulnerabilities
==========================================================================

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

- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in Zsh.

Software Description:
- zsh: shell with lots of features

Details:

Richard Maciel Costa discovered that Zsh incorrectly handled certain
inputs. An attacker could possibly use this to cause a denial of
service. (CVE-2018-1071)

It was discovered that Zsh incorrectly handled certain files. An
attacker could possibly use this to execute arbitrary code. 
(CVE-2018-1083)

Update instructions:

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

Ubuntu 17.10:
  zsh 5.2-5ubuntu1.2

Ubuntu 16.04 LTS:
  zsh 5.1.1-1ubuntu2.2

Ubuntu 14.04 LTS:
  zsh 5.0.2-3ubuntu6.2

After a standard system update you need to restart Zsh to make
all the necessary changes

References:
  https://usn.ubuntu.com/usn/usn-3608-1
  CVE-2018-1071, CVE-2018-1083

Package Information:
  https://launchpad.net/ubuntu/+source/zsh/5.2-5ubuntu1.2
  https://launchpad.net/ubuntu/+source/zsh/5.1.1-1ubuntu2.2
  https://launchpad.net/ubuntu/+source/zsh/5.0.2-3ubuntu6.2

USN-3609-1: Firefox vulnerability

==========================================================================
Ubuntu Security Notice USN-3609-1
March 27, 2018

firefox vulnerability
==========================================================================

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

- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Firefox could be made to crash or run programs as your login if it
opened a malicious website.

Software Description:
- firefox: Mozilla Open Source web browser

Details:

A use-after-free was discovered in Firefox. If a user were tricked in to
opening a specially crafted website, an attacker could potentially exploit
this to cause a denial of service or execute arbitrary code.

Update instructions:

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

Ubuntu 17.10:
firefox 59.0.2+build1-0ubuntu0.17.10.1

Ubuntu 16.04 LTS:
firefox 59.0.2+build1-0ubuntu0.16.04.1

Ubuntu 14.04 LTS:
firefox 59.0.2+build1-0ubuntu0.14.04.1

After a standard system update you need to restart Firefox to make
all the necessary changes.

References:
https://usn.ubuntu.com/usn/usn-3609-1
CVE-2018-5148

Package Information:
https://launchpad.net/ubuntu/+source/firefox/59.0.2+build1-0ubuntu0.17.10.1
https://launchpad.net/ubuntu/+source/firefox/59.0.2+build1-0ubuntu0.16.04.1
https://launchpad.net/ubuntu/+source/firefox/59.0.2+build1-0ubuntu0.14.04.1