[CVE-2026-78409] The X-mount.subdir option uses a detached-tree fast path on Linux 6.15 and later and passes the conf…

Descripción técnica

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.

Puntuación CVSS

Score: 7/10 — Severidad: HIGH — Estado NIST: Received

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

Debilidades (CWE)

CWE-59

Fuente oficial

Publicado en NIST NVD.