| Name | CVE-2026-78408 |
| Description | 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| util-linux (PTS) | bookworm | 2.38.1-5+deb12u3 | fixed |
| bookworm (security) | 2.38.1-5+deb12u1 | fixed |
| trixie (security), trixie | 2.41.5-0+deb13u1 | vulnerable |
| forky, sid | 2.42.4-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| util-linux | source | bookworm | (not affected) | | | |
| util-linux | source | (unstable) | 2.42.4-1 | | | |
Notes
[trixie] - util-linux <no-dsa> (Minor issue)
[bookworm] - util-linux <not-affected> (Vulnerable code not present, added in b40650b7, v2.40)
https://github.com/util-linux/util-linux/security/advisories/GHSA-55fx-f4gg-cfhj
Fixed by: https://github.com/util-linux/util-linux/commit/286dd3ff41526b582ef48830de239dffbaa61f90 (v2.42.4)