CVE-2026-89662

Full vulnerability record from the local CVENow database.

Description

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.

Severity

CRITICAL

CVSS score

9.8 (v3.1)

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-11 20:19:52.523000

Last modified

2026-10-19 09:18:04.083000

View original CVE JSON

{
  "id": "CVE-2026-89662",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-11T20:19:52.523",
  "lastModified": "2026-10-19T09:18:04.083",
  "vulnStatus": "Received",
  "cveTags": [],
  "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's 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->blocked_locks_lru independently of client state.\nThe two paths share blocked_locks_lock only for the list splice, not\nthe owner's 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."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "42d7954b0a1907d4ef122aef94561952a033cdc3",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "b8bad5a11416b26cc7fd4b18fba46d75ff636558",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "1ce74d1b7770e69735e8f8e509807af4ff9c8ee7",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "a6ead6fff3a7d03e49845f048f7000a2e0d34431",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "4804c58f73a80d12df1de323bf97a164f6ee8743",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "8cf4ff0a7c083dd5e0067f517d63979b74b66649",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "lessThan": "5e2fa29d223a9a1e6a948e40b109d09081d1decd",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "e294c4c2d33b7307a89cdf31bec08a112d6a9297",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "797bfd05d4040fbf766198b3cfcc1838002cc890",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "0f44e9da465ea259b6c9f31a627f3c50a16e1679",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "4.9.91",
              "lessThan": "4.10",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "4.14.31",
              "lessThan": "4.15",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "4.15.14",
              "lessThan": "4.16",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "4.16",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "4.16",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.270",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.221",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.188",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.157",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.109",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.50",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.4",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T19:25:37.406747Z",
          "id": "CVE-2026-89662",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1ce74d1b7770e69735e8f8e509807af4ff9c8ee7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/42d7954b0a1907d4ef122aef94561952a033cdc3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b8bad5a11416b26cc7fd4b18fba46d75ff636558",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}