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Ubuntu Security Notice USN-6088-2
May 23, 2023

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

- Ubuntu 16.04 LTS (Available with Ubuntu Pro)

Summary:

Several security issues were fixed in runC.

Software Description:
- runc: Open Container Project

Details:

USN-6088-1 fixed vulnerabilities in runC. This update provides
the corresponding updates for Ubuntu 16.04 LTS.

It was discovered that runC incorrectly performed access control when
mounting /proc to non-directories. An attacker could possibly use
this issue to escalate privileges.
(CVE-2019-19921)

Felix Wilhelm discovered that runC incorrecly handled netlink
messages. An attacker could possibly use
this issue to escalate privileges. (CVE-2021-43784)

Andrew G. Morgan discovered that runC incorrectly set
inherited process capabilities inside the container.
An attacker could possibly use this issue to
escalate privileges. (CVE-2022-29162)

Original advisory details:

  It was discovered that runC incorrectly made /sys/fs/cgroup
  writable when in rootless mode. An attacker could possibly
  use this issue to escalate privileges. (CVE-2023-25809)

  It was discovered that runC incorrectly performed access control when
  mounting /proc to non-directories. An attacker could possibly use
  this issue to escalate privileges. (CVE-2023-27561)

  It was discovered that runC incorrectly handled /proc and
  /sys mounts inside a container. An attacker could possibly
  use this issue to bypass AppArmor, and potentially SELinux.
  (CVE-2023-28642)

Update instructions:

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

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   runc 1.0.0~rc7+git20190403.029124da-0ubuntu1~16.04.4+esm4

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

References:
   https://ubuntu.com/security/notices/USN-6088-2
   https://ubuntu.com/security/notices/USN-6088-1
   CVE-2019-19921, CVE-2021-43784, CVE-2022-29162, CVE-2023-25809,
   CVE-2023-27561, CVE-2023-28642