containerd is an open source container runtime. A bug was found in containerd prior to versions 1.6.18 and 1.5.18 where supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases, potentially gaining access to sensitive information or gaining the ability to execute code in that container. Downstream applications that use the containerd client library may be affected as well.
This bug has been fixed in containerd v1.6.18 and v.1.5.18. Users should update to these versions and recreate containers to resolve this issue. Users who rely on a downstream application that uses containerds client library should check that application for a separate advisory and instructions. As a workaround, ensure that the USER $USERNAME Dockerfile instruction is not used. Instead, set the container entrypoint to a value similar to ENTRYPOINT [su, -, user] to allow su to properly set up supplementary groups.
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Containerd | Linuxfoundation | * | 1.5.18 (excluding) |
| Containerd | Linuxfoundation | 1.6.0 (including) | 1.6.18 (excluding) |
Assuming a user with a given identity, authorization is the process of determining whether that user can access a given resource, based on the user’s privileges and any permissions or other access-control specifications that apply to the resource. When access control checks are incorrectly applied, users are able to access data or perform actions that they should not be allowed to perform. This can lead to a wide range of problems, including information exposures, denial of service, and arbitrary code execution.