A containerd security update has been released for Ubuntu Linux 20.04 LTS and 20.10.

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Ubuntu Security Notice USN-4881-1
March 17, 2021

containerd vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS

Summary:

The system could be made to expose sensitive information.

Software Description:
- containerd: daemon to control runC

Details:

It was discovered that containerd incorrectly handled certain environment
variables. Contrary to expectations, a container could receive environment
variables defined for a different container, possibly containing sensitive
information.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.10:
containerd 1.3.7-0ubuntu3.3

Ubuntu 20.04 LTS:
containerd 1.3.3-0ubuntu2.3

After a standard system update you need to restart containerd to make
all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-4881-1
CVE-2021-21334

Package Information:
  https://launchpad.net/ubuntu/+source/containerd/1.3.7-0ubuntu3.3
  https://launchpad.net/ubuntu/+source/containerd/1.3.3-0ubuntu2.3