{"id":"CVE-2026-72034","title":"fhandle: reject detached mounts in capable_wrt_mount()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nfhandle: reject detached mounts in capable_wrt_mount()\n\nThe recent fhandle RCU fix moved the mount namespace capability check\ninto capable_wrt_mount(), so a non-NULL mn…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 15104234c267ebe04b9f9a73e5c2179cc265ff60","Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6c52226072a3c61337b1eec1799bb987748884fa","Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55","Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6c732471740bc2ac9b0946134f9f551dc75f4369","Linux 6.11"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:50:22.071900Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:53:17.001Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72034","references":[{"url":"https://git.kernel.org/stable/c/15104234c267ebe04b9f9a73e5c2179cc265ff60"},{"url":"https://git.kernel.org/stable/c/6c52226072a3c61337b1eec1799bb987748884fa"},{"url":"https://git.kernel.org/stable/c/6ee183d89261bf1d1cf9f06d80a40dab8f36ee55"},{"url":"https://git.kernel.org/stable/c/6c732471740bc2ac9b0946134f9f551dc75f4369"}],"tags":["cve.org"],"epss":0.00175,"epssPercentile":0.06557,"ingestedAt":"2026-10-16T17:24:46.871Z","slug":"CVE-2026-72034","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nfhandle: reject detached mounts in capable_wrt_mount()\n\nThe recent fhandle RCU fix moved the mount namespace capability check\ninto capable_wrt_mount(), so a non-NULL mnt_namespace survives the\nns_capable() dereference. The helper still assumes the later\nREAD_ONCE(mount->mnt_ns) must be non-NULL because may_decode_fh()\nchecked is_mounted() first.\n\nThat assumption is not stable. A detached mount from\nopen_tree(..., OPEN_TREE_CLONE) can be dissolved on fput while\nopen_by_handle_at() is between those checks, and umount_tree() can\nclear mount->mnt_ns. If the helper observes NULL, it dereferences\nmnt_ns->user_ns and panics.\n\nReturn false when the RCU read observes a detached mount. This keeps\nthe relaxed permission path conservative: a mount no longer attached\nto a namespace cannot authorize open_by_handle_at() access.\n\n## Affected\n\n- `Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 15104234c267ebe04b9f9a73e5c2179cc265ff60`\n- `Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6c52226072a3c61337b1eec1799bb987748884fa`\n- `Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55`\n- `Linux >= 620c266f394932e5decc4b34683a75dfc59dc2f4 < 6c732471740bc2ac9b0946134f9f551dc75f4369`\n- `Linux 6.11`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}