CVE-2026-78409
Util-linux: util-linux: x-mount.subdir detached-tree resolution can escape via intermediate symlinks
- State
- Published
- Severity
- 7.0 High
- Published
- Sep 2, 2026
- Updated
- Oct 21, 2026
- Reserved
- Aug 24, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.0 High | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H | redhat |
Weaknesses
- CWE-59 Improper Link Resolution Before File Access ('Link Following')
Affected Products
| Product | Versions |
|---|---|
Red Hat Hardened ImagesRed Hat |
|
Red Hat Enterprise Linux 10Red Hat | |
Red Hat Enterprise Linux 7Red Hat | |
Red Hat Enterprise Linux 8Red Hat | |
Red Hat Enterprise Linux 9Red Hat | |
Red Hat Enterprise Linux 9Red Hat | |
Red Hat Enterprise Linux 9Red Hat | |
Red Hat OpenShift Container Platform 4Red Hat | |
Red Hat OpenShift Container Platform 4Red Hat |
References
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