USN-3816-2: systemd vulnerability

19 November 2018

systemd vulnerability

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

  • Ubuntu 18.10
  • Ubuntu 18.04 LTS
  • Ubuntu 16.04 LTS

Summary

systemd-tmpfiles could be made to change ownership of arbitrary files.

Software Description

  • systemd - system and service manager

Details

USN-3816-1 fixed several vulnerabilities in systemd. However, the fix for CVE-2018-6954 was not sufficient. This update provides the remaining fixes.

We apologize for the inconvenience.

Original advisory details:

Jann Horn discovered that unit_deserialize incorrectly handled status messages above a certain length. A local attacker could potentially exploit this via NotifyAccess to inject arbitrary state across re-execution and obtain root privileges. (CVE-2018-15686)

Jann Horn discovered a race condition in chown_one(). A local attacker could potentially exploit this by setting arbitrary permissions on certain files to obtain root privileges. This issue only affected Ubuntu 18.04 LTS and Ubuntu 18.10. (CVE-2018-15687)

It was discovered that systemd-tmpfiles mishandled symlinks in non-terminal path components. A local attacker could potentially exploit this by gaining ownership of certain files to obtain root privileges. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. (CVE-2018-6954)

Update instructions

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

Ubuntu 18.10
systemd - 239-7ubuntu10.4
Ubuntu 18.04 LTS
systemd - 237-3ubuntu10.9
Ubuntu 16.04 LTS
systemd - 229-4ubuntu21.9

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

After a standard system update you need to reboot your computer to make all the necessary changes.

References