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EUVD-2026-367680

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 08:36

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T08:36:31.370829+00:00",
  "id": "EUVD-2026-367680"
}

CVE-2026-89662 (GCVE-0-2026-89662)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01

Title

NFSD: Prevent lock owner use-after-free during client teardown

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.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/42d7954b0a1907d4e…
https://git.kernel.org/stable/c/bb38ff8b4dafbbd17…
https://git.kernel.org/stable/c/b8bad5a11416b26cc…
https://git.kernel.org/stable/c/1ce74d1b7770e6973…
https://git.kernel.org/stable/c/a6ead6fff3a7d03e4…
https://git.kernel.org/stable/c/4804c58f73a80d12d…
https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e…
https://git.kernel.org/stable/c/5e2fa29d223a9a1e6…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < 42d7954b0a1907d4ef122aef94561952a033cdc3 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < b8bad5a11416b26cc7fd4b18fba46d75ff636558 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < a6ead6fff3a7d03e49845f048f7000a2e0d34431 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < 4804c58f73a80d12df1de323bf97a164f6ee8743 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < 8cf4ff0a7c083dd5e0067f517d63979b74b66649 (git) Affected: 68ef3bc3166468678d5e1fdd216628c35bd1186f , < 5e2fa29d223a9a1e6a948e40b109d09081d1decd (git) Affected: e294c4c2d33b7307a89cdf31bec08a112d6a9297 (git) Affected: 797bfd05d4040fbf766198b3cfcc1838002cc890 (git) Affected: 0f44e9da465ea259b6c9f31a627f3c50a16e1679 (git) Affected: 4.9.91 , < 4.10 (semver) Affected: 4.14.31 , < 4.15 (semver) Affected: 4.15.14 , < 4.16 (semver)
Linux	Linux	Affected: 4.16 Unaffected: 0 , < 4.16 (semver) Unaffected: 5.10.270 , ≤ 5.10.* (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "42d7954b0a1907d4ef122aef94561952a033cdc3",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "b8bad5a11416b26cc7fd4b18fba46d75ff636558",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "1ce74d1b7770e69735e8f8e509807af4ff9c8ee7",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "a6ead6fff3a7d03e49845f048f7000a2e0d34431",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "4804c58f73a80d12df1de323bf97a164f6ee8743",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "8cf4ff0a7c083dd5e0067f517d63979b74b66649",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "lessThan": "5e2fa29d223a9a1e6a948e40b109d09081d1decd",
              "status": "affected",
              "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e294c4c2d33b7307a89cdf31bec08a112d6a9297",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "797bfd05d4040fbf766198b3cfcc1838002cc890",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0f44e9da465ea259b6c9f31a627f3c50a16e1679",
              "versionType": "git"
            },
            {
              "lessThan": "4.10",
              "status": "affected",
              "version": "4.9.91",
              "versionType": "semver"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.31",
              "versionType": "semver"
            },
            {
              "lessThan": "4.16",
              "status": "affected",
              "version": "4.15.14",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.16"
            },
            {
              "lessThan": "4.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.270",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.221",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
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                },
                {
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                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
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                  "vulnerable": true
                },
                {
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                },
                {
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                },
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                  "versionStartIncluding": "4.15.14",
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                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in nfsd NFSv4.1 client teardown and blocked-lock handling, reached by remote COMPOUND RPCs on the in-kernel NFS server (TCP/UDP 2049). A network client drives EXCHANGE_ID, CREATE_SESSION, OPEN, blocking LOCK, DESTROY_SESSION, and DESTROY_CLIENTID into __destroy_client().\nAC:L - The attacker controls both sides of the race: one client holds a conflicting lock while another queues a blocked lock, then DESTROY_CLIENTID races with lock-grant/CB_NOTIFY_LOCK or the laundromat freeing that lockowner. Concurrent NFS requests create the race, and it can be retried.\nPR:N - Typical nfsd deployments use AUTH_SYS, which does not cryptographically authenticate the client. A remote peer that can reach an export can create NFSv4.1 state and issue DESTROY_CLIENTID without a local account or kernel capabilities on the server.\nUI:N - Exploitation requires only attacker-sent NFS RPCs against a running nfsd export. No victim user action such as mounting a filesystem or opening a local file on the server is required.\nS:U - The use-after-free occurs in kernel nfsd lock-owner state on the NFS server host and does not cross a separate security authority such as a VM, guest/host, or IOMMU boundary.\nC:H - This is a use-after-free of the nfs4_lockowner slab object. Reclaiming the freed owner lets an attacker control later reads of so_client and related pointers in remove_blocked_locks(), yielding a kernel information-disclosure primitive.\nI:H - The same UAF is exploitable for integrity: the freed lockowner includes so_ops function pointers and lo_blocked list heads, so heap reuse can hijack control flow or corrupt list pointers for an arbitrary kernel write.\nA:H - The bug is a kernel use-after-free of the lock owner and was observed as a NULL dereference in remove_blocked_locks(), which can oops or panic nfsd and take down the server."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T12:01:52.387Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
        }
      ],
      "title": "NFSD: Prevent lock owner use-after-free during client teardown",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89662",
    "datePublished": "2026-09-11T19:45:49.833Z",
    "dateReserved": "2026-09-11T19:38:34.744Z",
    "dateUpdated": "2026-09-14T12:01:52.387Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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EUVD-2026-367680

CVE-2026-89662 (GCVE-0-2026-89662)

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