CVE-2026-78408
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.11%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.9 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H
- EPSS
- 0.11% probability · 2th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-775
- Source
- secalert@redhat.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.