CVE-2026-78410
Util-linux: util-linux: restricted bind mounts do not pin the source, allowing x-mount.owner/group/mode redirection
What happened?
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.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| util-linuxRed Hat | unaffected: 0:2.40.2-18.el10_2.20 to < * | See vendor advisory |
| costmanagement/costmanagement-ui-rhel10Red Hat | unaffected: 1793825318 to < * | See vendor advisory |
| util-linux-mainRed Hat | unaffected: 2.42.2-3.4.hum1 to < * | See vendor advisory |
| util-linuxRed Hat | Default status: unaffected | See vendor advisory |
| util-linuxRed Hat | Default status: unaffected | See vendor advisory |
| rhel8/flatpak-runtimeRed Hat | Default status: unaffected | See vendor advisory |
| rhel8/flatpak-sdkRed Hat | Default status: unaffected | See vendor advisory |
| util-linuxRed Hat | Default status: unaffected | See vendor advisory |
| openshift/ose-rhel-coreos-8Red Hat | Default status: unaffected | See vendor advisory |
| openshift/ose-rhel-coreos-9Red Hat | Default status: unaffected | See vendor advisory |
| openshift/ose-rhel-coreos-9Red Hat | Default status: unaffected | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-78410
- https://access.redhat.com/errata/RHSA-2026:63162
- https://access.redhat.com/errata/RHSA-2026:93461
- https://access.redhat.com/errata/RHSA-2026:95365
- https://access.redhat.com/security/cve/CVE-2026-78410
- https://bugzilla.redhat.com/show_bug.cgi?id=2522684
- https://github.com/util-linux/util-linux/security/advisories/GHSA-rh77-686x-2f2m