{"api_version":"1","generated_at":"2026-10-24T05:57:56+00:00","cve":"CVE-2026-98976","urls":{"html":"https://cve.report/CVE-2026-98976","api":"https://cve.report/api/cve/CVE-2026-98976.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98976","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98976"},"summary":{"title":"namespace: keep the lock on a mount that a propagated copy is moved beneath","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: keep the lock on a mount that a propagated copy is moved beneath\n\nattach_recursive_mnt() transfers MNT_LOCKED from the top mount to the\nmount that is moved beneath it with MOVE_MOUNT_BENEATH. This allows the\nowner of a user namespace to replace its locked /proc or its root. The\nmount beneath takes on the job of covering the underlying mountpoint\nallowing the top mount to be unmounted.\n\nConsider two mount namespaces:\n\n(H) The host H has a shared mount P with a secret in P/d\n(Z) Z is a user namespace made from M. Its copy of P receives\n    propagation from the host's P and its copy of M's cover on P/d is\n    locked Z's owner must not get to see P/d.\n\nNow (H) mounts X on P/d. This propagates into (Z). The copy of X lands\nbeneath (Z)'s locked cover. The locked property is transfered from (Z)'s\ncover to the copy of X propagated beneath it. The cover is now unlocked.\n\nNow (H) unmounts X again. The copy of X in (Z) gets unmounted and the\ncovering mount is left unlocked on top of P/d. (Z) can now unmount it:\n\n    Z: umount2(P/d)             = EINVAL            /* the cover is locked */\n    H: mount X on P/d, umount X                     /* both propagate into Z /*\n    Z: umount2(P/d)             = 0                 /* the cover is now unlocked */\n    Z: read P/d/secret          = \"covered-by-root\" /* secret revealed */\n\nSo only transfer the locked property to the mount beneath for mounts the\ncaller has placed. A propagated copy that lands beneath a locked mount\nis locked as well so that the mount at the bottom of the stack carries a\nlock the way every check expects. The mount on top of it remains locked\nto ensure that it keeps covering even if the propagated mount is\nunmounted again.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-23 13:17:19","updated_at":"2026-10-23 13:17:19"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/d74d66aa708ccf2bc0b1e265a83fed0f2308d5c4","name":"https://git.kernel.org/stable/c/d74d66aa708ccf2bc0b1e265a83fed0f2308d5c4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f1f0c24ca701d7d3061c7f69f7450f1734c11745","name":"https://git.kernel.org/stable/c/f1f0c24ca701d7d3061c7f69f7450f1734c11745","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98976","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98976","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c62a4766937edec2962d52e583276b459b739f2d f1f0c24ca701d7d3061c7f69f7450f1734c11745 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c62a4766937edec2962d52e583276b459b739f2d d74d66aa708ccf2bc0b1e265a83fed0f2308d5c4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.1","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.11 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/namespace.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"f1f0c24ca701d7d3061c7f69f7450f1734c11745","status":"affected","version":"c62a4766937edec2962d52e583276b459b739f2d","versionType":"git"},{"lessThan":"d74d66aa708ccf2bc0b1e265a83fed0f2308d5c4","status":"affected","version":"c62a4766937edec2962d52e583276b459b739f2d","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/namespace.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.1"},{"lessThan":"7.1","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.11","versionStartIncluding":"7.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"7.1","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: keep the lock on a mount that a propagated copy is moved beneath\n\nattach_recursive_mnt() transfers MNT_LOCKED from the top mount to the\nmount that is moved beneath it with MOVE_MOUNT_BENEATH. This allows the\nowner of a user namespace to replace its locked /proc or its root. The\nmount beneath takes on the job of covering the underlying mountpoint\nallowing the top mount to be unmounted.\n\nConsider two mount namespaces:\n\n(H) The host H has a shared mount P with a secret in P/d\n(Z) Z is a user namespace made from M. Its copy of P receives\n    propagation from the host's P and its copy of M's cover on P/d is\n    locked Z's owner must not get to see P/d.\n\nNow (H) mounts X on P/d. This propagates into (Z). The copy of X lands\nbeneath (Z)'s locked cover. The locked property is transfered from (Z)'s\ncover to the copy of X propagated beneath it. The cover is now unlocked.\n\nNow (H) unmounts X again. The copy of X in (Z) gets unmounted and the\ncovering mount is left unlocked on top of P/d. (Z) can now unmount it:\n\n    Z: umount2(P/d)             = EINVAL            /* the cover is locked */\n    H: mount X on P/d, umount X                     /* both propagate into Z /*\n    Z: umount2(P/d)             = 0                 /* the cover is now unlocked */\n    Z: read P/d/secret          = \"covered-by-root\" /* secret revealed */\n\nSo only transfer the locked property to the mount beneath for mounts the\ncaller has placed. A propagated copy that lands beneath a locked mount\nis locked as well so that the mount at the bottom of the stack carries a\nlock the way every check expects. The mount on top of it remains locked\nto ensure that it keeps covering even if the propagated mount is\nunmounted again."}],"providerMetadata":{"dateUpdated":"2026-10-23T12:19:49.363Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/f1f0c24ca701d7d3061c7f69f7450f1734c11745"},{"url":"https://git.kernel.org/stable/c/d74d66aa708ccf2bc0b1e265a83fed0f2308d5c4"}],"title":"namespace: keep the lock on a mount that a propagated copy is moved beneath","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98976","datePublished":"2026-10-23T12:19:49.363Z","dateReserved":"2026-09-25T10:25:14.383Z","dateUpdated":"2026-10-23T12:19:49.363Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-23 13:17:19","lastModifiedDate":"2026-10-23 13:17:19","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98976","Ordinal":"1","Title":"namespace: keep the lock on a mount that a propagated copy is mo","CVE":"CVE-2026-98976","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98976","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: keep the lock on a mount that a propagated copy is moved beneath\n\nattach_recursive_mnt() transfers MNT_LOCKED from the top mount to the\nmount that is moved beneath it with MOVE_MOUNT_BENEATH. This allows the\nowner of a user namespace to replace its locked /proc or its root. The\nmount beneath takes on the job of covering the underlying mountpoint\nallowing the top mount to be unmounted.\n\nConsider two mount namespaces:\n\n(H) The host H has a shared mount P with a secret in P/d\n(Z) Z is a user namespace made from M. Its copy of P receives\n    propagation from the host's P and its copy of M's cover on P/d is\n    locked Z's owner must not get to see P/d.\n\nNow (H) mounts X on P/d. This propagates into (Z). The copy of X lands\nbeneath (Z)'s locked cover. The locked property is transfered from (Z)'s\ncover to the copy of X propagated beneath it. The cover is now unlocked.\n\nNow (H) unmounts X again. The copy of X in (Z) gets unmounted and the\ncovering mount is left unlocked on top of P/d. (Z) can now unmount it:\n\n    Z: umount2(P/d)             = EINVAL            /* the cover is locked */\n    H: mount X on P/d, umount X                     /* both propagate into Z /*\n    Z: umount2(P/d)             = 0                 /* the cover is now unlocked */\n    Z: read P/d/secret          = \"covered-by-root\" /* secret revealed */\n\nSo only transfer the locked property to the mount beneath for mounts the\ncaller has placed. A propagated copy that lands beneath a locked mount\nis locked as well so that the mount at the bottom of the stack carries a\nlock the way every check expects. The mount on top of it remains locked\nto ensure that it keeps covering even if the propagated mount is\nunmounted again.","Type":"Description","Title":"namespace: keep the lock on a mount that a propagated copy is mo"}]}}}