Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://access.redhat.com/errata/RHSA-2026:63162
- https://access.redhat.com/security/cve/CVE-2026-78408
- https://bugzilla.redhat.com/show_bug.cgi?id=2522497
- https://github.com/util-linux/util-linux/security/advisories/GHSA-55fx-f4gg-cfhj
- http://www.openwall.com/lists/oss-security/2026/09/05/2
- https://github.com/util-linux/util-linux/security/advisories/GHSA-55fx-f4gg-cfhj
FAQ
What is CVE-2026-78408?
CVE-2026-78408 is a vulnerability with a CVSS score of 7.9 (HIGH). 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 c...
How severe is CVE-2026-78408?
CVE-2026-78408 has been rated HIGH with a CVSS base score of 7.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-78408?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.