A runC security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, 20.10, and 21.04.

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Ubuntu Security Notice USN-4960-1
May 19, 2021

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

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

runC could be made to overwrite files as the administrator.

Software Description:
- runc: Open Container Project

Details:

Etienne Champetier discovered that runC incorrectly checked mount targets.
An attacker with a malicious container image could possibly mount the host
filesystem into the container and escalate privileges.

Update instructions:

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

Ubuntu 21.04:
runc 1.0.0~rc93-0ubuntu1.1

Ubuntu 20.10:
runc 1.0.0~rc93-0ubuntu1~20.10.2

Ubuntu 20.04 LTS:
runc 1.0.0~rc93-0ubuntu1~20.04.2

Ubuntu 18.04 LTS:
runc 1.0.0~rc93-0ubuntu1~18.04.2

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-4960-1
CVE-2021-30465

Package Information:
  https://launchpad.net/ubuntu/+source/runc/1.0.0~rc93-0ubuntu1.1
  https://launchpad.net/ubuntu/+source/runc/1.0.0~rc93-0ubuntu1~20.10.2
  https://launchpad.net/ubuntu/+source/runc/1.0.0~rc93-0ubuntu1~20.04.2
  https://launchpad.net/ubuntu/+source/runc/1.0.0~rc93-0ubuntu1~18.04.2