# CVE-2026-78410: Util-linux: util-linux: restricted bind mounts do not pin the source, allowing x-mount.owner/group/mode redirection

Status: published. Published: 2026-09-02. Updated: 2026-11-02.

A flaw was found in util-linux. Restricted bind mounts take the source path from fstab but do not pin that source before the privileged mount. A local unprivileged user who can replace the authorized source or a writable ancestor can redirect SUID mount(8) to bind another host directory. If the fstab entry also sets X-mount.owner, X-mount.group, or X-mount.mode, root then changes ownership or mode on that redirected inode.

## Remediation

- workaround: Upgrade to util-linux v2.41.6, v2.42.3, or later. Until a fix is applied, do not allow unprivileged /etc/fstab bind or rbind entries that also specify X-mount.owner, X-mount.group, or X-mount.mode, especially when the bind source is below a user-writable ancestor. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (util-linux): ≥ 0:2.40.2-18.el10_2.20; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (util-linux-main): ≥ 2.42.2-3.4.hum1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (util-linux): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (util-linux): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (rhel8/flatpak-runtime): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (rhel8/flatpak-sdk): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (util-linux): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.8 (high); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-01; percentile 5.35%

- SSVC: exploitation poc; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-367

## Exploit evidence

- exploit: https://github.com/util-linux/util-linux/security/advisories/GHSA-rh77-686x-2f2m (ADP: CISA-ADP)

## References

- https://access.redhat.com/errata/RHSA-2026:63162 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:93461 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-78410 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2522684 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/util-linux/util-linux/security/advisories/GHSA-rh77-686x-2f2m (CNA: redhat)

- https://github.com/util-linux/util-linux/security/advisories/GHSA-rh77-686x-2f2m (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-78410; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-78410; retrieved 2026-11-02; source updated Not reported

Revision: 9c604f5a0b5dccdbbe524e16196d1bec2b5b460c69bc3961c21fae6b3c4f27bc

Canonical: https://y2.dev/cve/CVE-2026-78410