CVE-2026-89686

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid.

Severity

CRITICAL

CVSS score

9.8 (v3.1)

Vulnerability status

Received

Source identifier

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

Published

2026-09-11 20:19:55.533000

Last modified

2026-10-30 13:20:26.500000

View original CVE JSON

{
  "id": "CVE-2026-89686",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-11T20:19:55.533",
  "lastModified": "2026-10-30T13:20:26.500",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent stateid is a delegation. A concurrent delegation\nrevoke via the laundromat can clear fi_deleg_file under fi_lock, causing\nnfsd_file_get() to return NULL and triggering the BUG_ON.\n\nThis race is client-reachable: two NFS clients can trigger it by having\none hold a delegation while another opens the same file to force a\nrecall. When the first client doesn't respond to the recall, the\nlaundromat revokes it. A concurrent LAYOUTGET from any client using the\ndelegation stateid hits the race window.\n\nFix this by taking fi_lock around the fi_deleg_file read in the\nSC_TYPE_DELEG path, matching the locking discipline of the\nfind_any_file() arm, and replacing the BUG_ON with a graceful error\nreturn that cleans up the partially-initialized layout stateid."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/nfsd/nfs4layouts.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "f5011c26246d1abed3dc750c9744e33cb79ff9bc",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "d12af460df27876661707efab3a8532146cb961f",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "c517f27498757e616d2a8fe6d16caad1fee422e6",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "607a56fea772c1f4f4989d8e255dd4f7192d9604",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "97bda8b4284d90897a1f1922e5082ff9e35d7c7e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "c5c707f96fc9a6e5a57ca5baac892673270abe3d",
              "lessThan": "ca94ba36172046be6a694a7986f6931e47ed4d51",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/nfsd/nfs4layouts.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "4.0",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "4.0",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "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": "2026-10-16T19:26:03.140311Z",
          "id": "CVE-2026-89686",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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}