CVE-2026-89662 (GCVE-0-2026-89662)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-19 08:50
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
References
Impacted products
Vendor Product Version
Linux Linux Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: 68ef3bc3166468678d5e1fdd216628c35bd1186f
Version: e294c4c2d33b7307a89cdf31bec08a112d6a9297
Version: 797bfd05d4040fbf766198b3cfcc1838002cc890
Version: 0f44e9da465ea259b6c9f31a627f3c50a16e1679
Version: 4.9.91   ≤
Version: 4.14.31   ≤
Version: 4.15.14   ≤
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    "cveId": "CVE-2026-89662",
    "datePublished": "2026-09-11T19:45:49.833Z",
    "dateReserved": "2026-09-11T19:38:34.744Z",
    "dateUpdated": "2026-10-19T08:50:33.792Z",
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\"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"4.16\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"4.16\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.270\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.221\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.188\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.157\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.109\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.50\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.2.4\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.2.*\"}, {\"status\": \"unaffected\", \"version\": \"7.3\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"fs/nfsd/nfs4state.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/42d7954b0a1907d4ef122aef94561952a033cdc3\"}, {\"url\": \"https://git.kernel.org/stable/c/bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a\"}, {\"url\": \"https://git.kernel.org/stable/c/b8bad5a11416b26cc7fd4b18fba46d75ff636558\"}, {\"url\": \"https://git.kernel.org/stable/c/1ce74d1b7770e69735e8f8e509807af4ff9c8ee7\"}, {\"url\": \"https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431\"}, {\"url\": \"https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743\"}, {\"url\": \"https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649\"}, {\"url\": \"https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nNFSD: Prevent lock owner use-after-free during client teardown\\n\\n__destroy_client() releases a client\u0027s open owners, but a lock owner\\nwhose only reference is a blocked lock (nbl) stays on\\ncl_ownerstr_hashtbl.  client_has_state() does not count a bare owner,\\nso DESTROY_CLIENTID can reach __destroy_client() with such owners\\npresent.\\n\\n__destroy_client() then walks the table, calling remove_blocked_locks()\\non each owner without a reference.  Freeing a blocked lock drops the\\nowner reference held via flc_owner.  The per-net laundromat reaps\\nblocked locks from nn-\u003eblocked_locks_lru independently of client state.\\nThe two paths share blocked_locks_lock only for the list splice, not\\nthe owner\u0027s lifetime.  The laundromat therefore frees the owner as\\n__destroy_client() dereferences it, a NULL dereference in\\nremove_blocked_locks().\\n\\nnfsd4_release_lockowner() holds a reference across the same call;\\n__destroy_client() does not.  Hold cl_lock across the walk, taking a\\nreference and unhashing each owner, then drop it before\\nremove_blocked_locks() and nfs4_put_stateowner(), which take\\nblocked_locks_lock and cl_lock.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.270\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.221\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.188\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.157\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.109\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.50\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.2.4\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.3\", \"versionStartIncluding\": \"4.16\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.9.91\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.14.31\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.15.14\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-10-19T08:50:33.792Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-89662\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T08:50:33.792Z\", \"dateReserved\": \"2026-09-11T19:38:34.744Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-09-11T19:45:49.833Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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