Ubuntu Security Notice 3816-2 - USN-3816-1 fixed several vulnerabilities in systemd. However, the fix for CVE-2018-6954 was not sufficient. This update provides the remaining fixes. 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. 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. 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. Various other issues were also addressed.
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Ubuntu Security Notice USN-3816-2
November 19, 2018
systemd vulnerability
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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
After a standard system update you need to reboot your computer to make
all the necessary changes.
References:
https://usn.ubuntu.com/usn/usn-3816-2
https://usn.ubuntu.com/usn/usn-3816-1
CVE-2018-6954
Package Information:
https://launchpad.net/ubuntu/+source/systemd/239-7ubuntu10.4
https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.9
https://launchpad.net/ubuntu/+source/systemd/229-4ubuntu21.9