=========================================================================Ubuntu Security Notice USN-3938-1
April 08, 2019

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

- Ubuntu 18.10
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

The systemd PAM module could be used to gain additional PolicyKit
privileges.

Software Description:
- systemd: system and service manager

Details:

Jann Horn discovered that pam_systemd created logind sessions using some
parameters from the environment. A local attacker could exploit this in
order to spoof the active session and gain additional PolicyKit
privileges.

Update instructions:

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

Ubuntu 18.10:
  libpam-systemd                  239-7ubuntu10.12

Ubuntu 18.04 LTS:
  libpam-systemd                  237-3ubuntu10.19

Ubuntu 16.04 LTS:
  libpam-systemd                  229-4ubuntu21.21

Ubuntu 14.04 LTS:
  libpam-systemd                  204-5ubuntu20.31

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

References:
  
  CVE-2019-3842

Package Information:
  https://launchpad.net/ubuntu/+source/systemd/239-7ubuntu10.12
  https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.19
  https://launchpad.net/ubuntu/+source/systemd/229-4ubuntu21.21
  https://launchpad.net/ubuntu/+source/systemd/204-5ubuntu20.31