{"schema":"threatline.record/2","record":{"id":"CVE-2026-98990","aliases":[],"summary":"namespace: check a submount for references right before unmounting it","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: check a submount for references right before unmounting it\n\nshrink_submounts() and mark_mounts_for_expiry() first collect all the\nmounts they are allowed to unmount and then unmount them.\n\nWhether a mount is busy is decided by propagate_mount_busy() on the\ntree. But unmounting the first mount changes the tree that the second\none propagates into. propagate_umount()\nmoves a surviving overmount off a copy it unmounts and mounts it where\nthe copy was mounted. If that's where the propagated copy of the second\nvictim is looked up the overmount becomes a candidate of the second\numount_tree(). It's childless and so trim_one() commits it without\nlooking at its reference count.\n\nSo a synchronous umount pulls out a busy mount that is in use somewhere\nelse and marks it MNT_SYNC_UMOUNT while it has users:\n\n  umount2(/tmp/plshrink/p1, 0) = 0 errno 0\n  cwd is (unreachable)\n\nThe same two umounts requested one after the other fail with EBUSY.\nThis needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of\nNFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts\ninherit the flag.\n\nCheck each mount right before it is unmounted under the same hold of\nnamespace_sem and mount_lock as the umount itself. Make sure that the\nalgorithm stays linear.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"1064f874abc0d05eeed8993815f584d847b72486","lessThan":"f6394281834492c6516a405a348b545ae698a331","status":"affected","versionType":"git"},{"version":"1064f874abc0d05eeed8993815f584d847b72486","lessThan":"6e4012e571867868b545c91ca9d6095fdb709907","status":"affected","versionType":"git"},{"version":"1064f874abc0d05eeed8993815f584d847b72486","lessThan":"d73f04e92c1aab78d96ac6cadb234c8a3a373d22","status":"affected","versionType":"git"},{"version":"1064f874abc0d05eeed8993815f584d847b72486","lessThan":"18902a23ef36f83d32bafc58ae2484e6bb4bb8ef","status":"affected","versionType":"git"},{"version":"1064f874abc0d05eeed8993815f584d847b72486","lessThan":"32bf92416614a1e3ff3524fc6b780259c7aad3ef","status":"affected","versionType":"git"},{"version":"5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf","status":"affected","versionType":"git"},{"version":"839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7","status":"affected","versionType":"git"},{"version":"808e83e5add13152bd4a88346487de68395c136b","status":"affected","versionType":"git"},{"version":"6de9d08a9718ee9c12ba6343c50141c2d633e3dc","status":"affected","versionType":"git"},{"version":"4.1.40","lessThan":"4.2","status":"affected","versionType":"semver"},{"version":"4.4.54","lessThan":"4.5","status":"affected","versionType":"semver"},{"version":"4.9.15","lessThan":"4.10","status":"affected","versionType":"semver"},{"version":"4.10.3","lessThan":"4.11","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"4.11","status":"affected"},{"version":"0","lessThan":"4.11","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.113","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.57","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.11","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"6e4012e571867868b545c91ca9d6095fdb709907","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"18902a23ef36f83d32bafc58ae2484e6bb4bb8ef","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"32bf92416614a1e3ff3524fc6b780259c7aad3ef","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"4.2","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"4.5","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"4.10","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","source_modified_at":"2026-10-23T12:20:09.349Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"4.11","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-23T12:20:09.349Z","modified_at":"2026-10-23T12:20:09.349Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98990","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23T12:20:09.349Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/f6394281834492c6516a405a348b545ae698a331"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/6e4012e571867868b545c91ca9d6095fdb709907"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/d73f04e92c1aab78d96ac6cadb234c8a3a373d22"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/18902a23ef36f83d32bafc58ae2484e6bb4bb8ef"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/32bf92416614a1e3ff3524fc6b780259c7aad3ef"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-23T12:20:09.349Z","content_hash":"071fb454a5ff9579b65442f9e0475f6cc12709919d63033cdac3e5df5b7729b9"}}