Description
The X-mount.subdir option uses a detached-tree fast path on Linux 6.15 and later and passes the configured subdirectory to open_tree() with AT_SYMLINK_NOFOLLOW. That flag does not stop intermediate symlink traversal or keep resolution inside the newly mounted filesystem. A local unprivileged user with an fstab-authorized X-mount.subdir entry can attach a host path at the intended mountpoint.
Metrics
CVSS 3.1 7.0/10
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HWeakness enumeration
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Hardened Images | — |
| Red Hat | Red Hat Enterprise Linux 10 | — |
| Red Hat | Red Hat Enterprise Linux 7 | — |
| Red Hat | Red Hat Enterprise Linux 8 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — |
References
- https://access.redhat.com/errata/RHSA-2026:63162
- https://access.redhat.com/security/cve/CVE-2026-78409
- https://bugzilla.redhat.com/show_bug.cgi?id=2522607
- https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv
- https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv
Timeline
- Published
- Sep 2, 2026
- Last modified
- Nov 5, 2026
- NVD status
- Awaiting Analysis