CVE-2026-78409
HIGH
MEDIUM
Priority: 0.01
BB Relevance:
29/100
Published: 2026-09-02
Modified: 2026-11-05
First seen: 2026-11-05
Status: active
Attack Surface
No Interaction
Conf. Impact
Integ. Impact
CVSS Vector Breakdown
AV:
Local
AC:
High
PR:
Low
UI:
None
S:
Unchanged
C:
High
I:
High
A:
High
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.
Weakness Classification (1)
References & Advisories (4)
vendor-advisory
x_refsource_REDHAT
vdb-entry
x_refsource_REDHAT
issue-tracking
x_refsource_REDHAT