Published: 10 February 2021
When generating the systemd service units for the docker snap (and other similar snaps), snapd does not specify Delegate=yes - as a result systemd will move processes from the containers created and managed by these snaps into the cgroup of the main daemon within the snap itself when reloading system units. This may grant additional privileges to a container within the snap that were not originally intended.
From the Ubuntu security team
Gilad Reti and Nimrod Stoler discovered that snapd did not correctly specify cgroup delegation when generating systemd service units for various container management snaps. This could allow a local attacker to escalate privileges via access to arbitrary devices of the container host from within a compromised or malicious container.
CVSS 3 base score: 9.3
Launchpad, Ubuntu, Debian
|Ubuntu 20.10 (Groovy Gorilla)||
|Ubuntu 20.04 LTS (Focal Fossa)||
|Ubuntu 18.04 LTS (Bionic Beaver)||
|Ubuntu 16.04 ESM (Xenial Xerus)||
|Ubuntu 14.04 ESM (Trusty Tahr)||
Does not exist