Affected: Alpaquita:stream: util-linux, BellSoft Hardened Containers:stream: util-linux

The nsenter --join-cgroup option opens the target cgroup.procs file as root and leaves that file descriptor open across later namespace and credential changes and across execve(). Because the kernel checks later cgroup migrations using the credentials from the original open, a program run in an attacker-controlled target can inherit root's ability to move host processes between cgroups. After a privileged operator uses --join-cgroup against that target, an unprivileged user can migrate and terminate unrelated root processes.

libblkid-devel-2.42.3-1.1 on GA media

util-linux: util-linux: failed external mount helper still runs privileged X-mount post-hooks util-linux: util-linux: nsenter --join-cgroup leaks root cgroup migration authority util-linux: util-linux: X-mount.subdir detached-tree resolution can escape via intermediate symlinks util-linux: util-linux: restricted bind mounts do not pin the source, allowing X-mount.owner/group/mode redirection

Security update for util-linux

Affected: Ubuntu:14.04:LTS: util-linux, Ubuntu:Pro:16.04:LTS: util-linux, Ubuntu:18.04:LTS: util-linux, Ubuntu:Pro:20.04:LTS: util-linux, Ubuntu:22.04:LTS: util-linux, Ubuntu:24.04:LTS: util-linux, Ubuntu:26.04:LTS: util-linux

The nsenter --join-cgroup option opens the target cgroup.procs file as root and leaves that file descriptor open across later namespace and credential changes and across execve(). Because the kernel checks later cgroup migrations using the credentials from the original open, a program run in an attacker-controlled target can inherit root's ability to move host processes between cgroups. After a privileged operator uses --join-cgroup against that target, an unprivileged user can migrate and terminate unrelated root processes.