{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-78409","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","state":"PUBLISHED","assignerShortName":"redhat","dateReserved":"2026-08-24T14:40:18.012Z","datePublished":"2026-09-02T15:11:47.184Z","dateUpdated":"2026-09-03T12:50:56.499Z"},"containers":{"cna":{"title":"Util-linux: util-linux: x-mount.subdir detached-tree resolution can escape via intermediate symlinks","metrics":[{"other":{"content":{"value":"Important","namespace":"https://access.redhat.com/security/updates/classification/"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Red Hat","product":"Red Hat Hardened Images","collectionURL":"https://catalog.redhat.com/software/containers/","packageName":"util-linux-main","defaultStatus":"affected","versions":[{"version":"2.42.2-3.4.hum1","lessThan":"*","versionType":"rpm","status":"unaffected"}],"cpes":["cpe:/a:redhat:hummingbird:1"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"util-linux","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"util-linux","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"util-linux","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhel8/flatpak-runtime","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhel8/flatpak-sdk","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"util-linux","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","defaultStatus":"unaffected","cpes":["cpe:/a:redhat:openshift:4"]}],"references":[{"url":"https://access.redhat.com/errata/RHSA-2026:63162","name":"RHSA-2026:63162","tags":["vendor-advisory","x_refsource_REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-78409","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2522607","name":"RHBZ#2522607","tags":["issue-tracking","x_refsource_REDHAT"]},{"url":"https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv"}],"datePublic":"2026-09-02T00:00:00.000Z","problemTypes":[{"descriptions":[{"cweId":"CWE-59","description":"Improper Link Resolution Before File Access ('Link Following')","lang":"en","type":"CWE"}]}],"x_redhatCweChain":"CWE-59: Improper Link Resolution Before File Access ('Link Following')","workarounds":[{"lang":"en","value":"Upgrade to util-linux v2.41.6, v2.42.3, or later. Until a fix is applied, do not allow unprivileged /etc/fstab entries that specify X-mount.subdir."}],"timeline":[{"lang":"en","time":"2026-06-17T00:00:00.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-09-02T00:00:00.000Z","value":"Made public."}],"credits":[{"lang":"en","value":"Upstream acknowledges Zhuorao Yang (Huawei Cloud) as the original reporter."}],"providerMetadata":{"orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","shortName":"redhat","dateUpdated":"2026-09-03T12:50:56.499Z"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"references":[{"url":"https://github.com/util-linux/util-linux/security/advisories/GHSA-8f2p-47x3-43mv","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-02T15:29:06.011028Z","id":"CVE-2026-78409","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-02T15:31:33.985Z"}}]}}