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VULNERABILITIES

CVE-2026-78409 Details

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.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:7 HIGHVector:CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv CISA-ADP
https://access.redhat.com/errata/RHSA-2026:63162 [email protected]
https://access.redhat.com/security/cve/CVE-2026-78409 [email protected]
https://bugzilla.redhat.com/show_bug.cgi?id=2522607 [email protected]
https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv [email protected]

Weakness Enumeration

CWE-IDCWE NameSource
CWE-59Improper Link Resolution Before File Access ('Link Following')[email protected]

Affected Products

No affected product data is available for this CVE.

Change History

3 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-78409
NVD Published Date:
Sep 2, 2026
NVD Last Modified:
Sep 3, 2026
Source:
[email protected]
CVE-2026-78409 Details - Not Deferred