{"schema":"threatline.record/2","record":{"id":"CVE-2026-98991","aliases":[],"summary":"namespace: queue a mount only once for mount notifications","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: queue a mount only once for mount notifications\n\nmnt_notify_add() puts a mount on notify_list. It doesn't check whether\nthe mount is on the list already. That's fine as long as every mount is\nqueued at most once per namespace_sem hold. It isn't.\n\npropagate_umount() moves a surviving overmount off a stack of mounts\nthat are going away and queues it as moved. shrink_submounts() and\nmark_mounts_for_expiry() call umount_tree() for several mounts under a\nsingle namespace_sem hold. So the second umount_tree() can take down\nexactly the mount the first one reparented, reparent it once more and so\nend up queueing it a second time.\n\nThe second list_add_tail() cuts the mounts queued in between out of the\nlist while the head still points at the last of them. notify_mnt_list()\nthen only visits that one mount and the others are freed after the grace\nperiod with notify_list still pointing at them. Every later mount\noperation on the host walks freed memory:\n\n  BUG: KASAN: slab-use-after-free in __list_add_valid_or_report\n  Read of size 8 at addr ffff8881003d57e0 by task notify_dq/162\n   __list_add_valid_or_report+0x15c/0x1a0\n   mnt_add_to_ns+0x322/0x890\n   attach_recursive_mnt.isra.0+0xf2a/0x1a00\n   path_mount+0x139c/0x1d40\n\nThis needs a mount with MNT_SHRINKABLE to bind from. That's what\nfinish_automount() creates (submounts of NFS, AFS and CIFS and the\ntracefs mount below debugfs). Bind mounts inherit the flag. A mount\nnamespace with a FAN_MARK_MNTNS mark does the rest and root in a user\nnamespace can have both.\n\nInitialize to_notify in alloc_vfsmnt() and leave a mount alone that is\nqueued already. mnt_notify() looks at the state the mount has when the\nlist is drained so a single entry per mount is enough. The move event\nfor a mount that is unmounted under the same hold is lost. That's fine.\nThe detach is what matters.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98991","source_modified_at":"2026-10-24T14:09:52.901Z","fetched_at":"2026-10-24T14:26:37.433577Z","product":"Linux","vendor":"Linux","versions":[{"lessThan":"acbe9e4418e2ef7bef1a12e62e0e7d6145a15190","status":"affected","version":"bf630c40164162ba1d3933c2f5e3397d083e0948","versionType":"git"},{"lessThan":"702ff3fe499876e09c45558a05366d21a5bc41ab","status":"affected","version":"bf630c40164162ba1d3933c2f5e3397d083e0948","versionType":"git"},{"lessThan":"bd2feb7796b6585938a4241e7b7c4148a6f7b762","status":"affected","version":"bf630c40164162ba1d3933c2f5e3397d083e0948","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98991","source_modified_at":"2026-10-24T14:09:52.901Z","fetched_at":"2026-10-24T14:26:37.433577Z","product":"Linux","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.57","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98991","source_modified_at":"2026-10-24T14:09:52.901Z","fetched_at":"2026-10-24T14:26:37.433577Z","package":{"name":"Linux","ecosystem":null},"version":"702ff3fe499876e09c45558a05366d21a5bc41ab","basis":"first unaffected version stated in the CVE record"}],"cvss":7.8,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00206,"percentile":0.10151,"score_date":"2026-10-24"},"published_at":"2026-10-23T12:20:10.289Z","modified_at":"2026-10-24T14:09:52.901Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98991","fetched_at":"2026-10-24T14:26:37.433577Z","source_modified_at":"2026-10-24T14:09:52.901Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98991","fetched_at":"2026-10-24T18:03:20.872036Z","source_modified_at":"2026-10-24"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/acbe9e4418e2ef7bef1a12e62e0e7d6145a15190"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/702ff3fe499876e09c45558a05366d21a5bc41ab"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/bd2feb7796b6585938a4241e7b7c4148a6f7b762"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-24T14:09:52.901Z","content_hash":"a0794875995238faaa8df0c6d02495f64cd5cb4eab248b64867f6da7cf9231c6"}}