CVE-2018-6556 The lxc-user-nic component of LXC allows unprivileged users to open arbitrary files
Unprivileged users can open arbitrary files or special kernel files via lxc-user-nic, enabling path existence checks and potential side effects.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2018-6556?
CVE-2018-6556 is a low-severity path traversal vulnerability in Canonical Ubuntu Linux, published on 10 Aug 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.
Weakness: CWE-417
Which versions are affected by CVE-2018-6556?
It affects 6 products.
Linux distribution packages (1)
lxc SUSE:Package Hub 15 | All versions | 2.0.9-bp150.5.6.1 |
Products include Canonical Ubuntu Linux, Linuxcontainers Lxc, Opensuse Leap, Suse Caas Platform, Suse Openstack Cloud, Suse Suse Linux Enterprise Server.
How do I fix CVE-2018-6556?
Apply the vendor's patch.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2018-6556 being exploited?
There is no known exploitation of CVE-2018-6556 in the wild and no public exploit code.
Other vulnerabilities in Canonical Ubuntu Linux
Sources
Also known as ALPINE-CVE-2018-6556, DEBIAN-CVE-2018-6556, GHSA-xg68-6jxg-5w7p, UBUNTU-CVE-2018-6556, USN-3730-1, openSUSE-SU-2019:1230-1.