CVE-2026-78409
Util-linux: util-linux: x-mount.subdir detached-tree resolution can escape via intermediate symlinks
CVSS Score
7.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-59 |
| Vendor | red hat |
| Product | red hat hardened images |
| Published | Sep 2, 2026 |
| Last Updated | Sep 3, 2026 |
Stay Ahead of the Next One
Get instant alerts for red hat red hat hardened images
Be the first to know when new high vulnerabilities affecting red hat red hat hardened images are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
Red Hat / Red Hat Hardened Images
All versions affected Red Hat / Red Hat Enterprise Linux 10
All versions affected Red Hat / Red Hat Enterprise Linux 7
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat OpenShift Container Platform 4
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2026:63162 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-78409 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2522607 github.com: https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv
Credits
Upstream acknowledges Zhuorao Yang (Huawei Cloud) as the original reporter.