CVE-2026-78409

Published: Sep 2, 2026Modified: Sep 3, 2026

7.0

Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitability: 1.0 / Impact: 5.9

Source: secalert@redhat.com (Secondary)

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.

Related CWEs

CWE-59

Improper Link Resolution Before File Access ('Link Following')

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

References (5)

https://access.redhat.com/errata/RHSA-2026:63162

Source: secalert@redhat.com

https://access.redhat.com/security/cve/CVE-2026-78409

Source: secalert@redhat.com

https://bugzilla.redhat.com/show_bug.cgi?id=2522607

Source: secalert@redhat.com

https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv

Source: secalert@redhat.com

https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Timeline

No history available yet.