USN-6088-2: runC vulnerabilities

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)