CVE-2026-78408 vulnerability in Red Hat Products
Published on September 2, 2026
Util-linux: util-linux: nsenter --join-cgroup leaks root cgroup migration authority
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.
Vulnerability Analysis
CVE-2026-78408 is exploitable with local system access, requires user interaction and a small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity and availability.
Timeline
Reported to Red Hat.
Made public. 38 days later.
Weakness Type
Missing Release of File Descriptor or Handle after Effective Lifetime
The software does not release a file descriptor or handle after its effective lifetime has ended, i.e., after the file descriptor/handle is no longer needed. When a file descriptor or handle is not released after use (typically by explicitly closing it), attackers can cause a denial of service by consuming all available file descriptors/handles, or otherwise preventing other system processes from obtaining their own file descriptors/handles.
Products Associated with CVE-2026-78408
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