systemd-tmpfiles could be made to change ownership of arbitrary files.
- systemd: system and service manager
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
above a certain length. A local attacker could potentially exploit this via
NotifyAccess to inject arbitrary state across re-execution and obtain root
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)
The problem can be corrected by updating your system to the following
Ubuntu 18.04 LTS:
Ubuntu 16.04 LTS:
After a standard system update you need to reboot your computer to make
all the necessary changes.