CVE-2020-27352
Publication date 10 February 2021
Last updated 25 August 2025
Ubuntu priority
Description
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| snapd | ||
| 20.04 LTS focal |
Fixed 2.48.3+20.04
|
|
| 18.04 LTS bionic |
Fixed 2.48.3+18.04
|
|
| 16.04 LTS xenial |
Fixed 2.48.3
|
|
| 14.04 LTS trusty | Not in release |
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
9.3 · Critical
|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Changed |
| Confidentiality | High |
| Integrity impact | High |
| Availability impact | High |
| Vector | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
References
Related Ubuntu Security Notices (USN)
- USN-4728-1
- snapd vulnerability
- 10 February 2021