Crun incorrectly parses `crun exec` option `-u`, leading to privilege escalation

crun is an open source OCI Container Runtime fully written in C. In versions 1.19 through 1.26, the `crun exec` option `-u` (`--user`) is incorrectly parsed. The value `1` is interpreted as UID 0 and GID 0 when it should have been UID 1 and GID 0. The process thus runs with higher privileges than expected. Version 1.27 patches the issue.

crun: Default inheritable capabilities for linux container should be empty

A flaw was found in crun where containers were incorrectly started with non-empty default permissions. A vulnerability was found in Moby (Docker Engine) where containers were started incorrectly with non-empty inheritable Linux process capabilities. This flaw allows an attacker with access to programs with inheritable file capabilities to elevate those capabilities to the permitted set when execve(2) runs.

An issue was discovered in crun before 0.10.5. With a crafted image, it doesn't correctly check whether a target is a symlink, resulting in access to files outside of the container. This occurs in libcrun/linux.c and libcrun/chroot_realpath.c.