{"cve":"CVE-2026-78409","nvd":{"published":"2026-09-02T16:17:23.833","modified":"2026-10-21T18:17:28.967","status":"Awaiting Analysis","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.0},"cwes":["CWE-59"],"references":["https://access.redhat.com/errata/RHSA-2026:63162","https://access.redhat.com/security/cve/CVE-2026-78409","https://bugzilla.redhat.com/show_bug.cgi?id=2522607","https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv","https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv"],"products":[],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-78409","score":0.00189,"percentile":0.0848,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}