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CVE-2026-89667

Estado: RecibidaAlta (8.1)—

In the Linux kernel, the following vulnerability has been resolved:

nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache

The shrinker, GC worker, and fsnotify/lease callbacks can unhash an nfsd_file from the rhashtable and then call nfsd_file_dispose_list_delayed() to move it to the per-net dispose list. If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk misses the already-unhashed file, and its drain of the per-net dispose list can run before the file has been queued. The file then sits on the per-net list with no thread to drain it, leaking both the file and its associated state.

Leer descripción completaMostrar menos

The GC worker and shrinker already hold nfsd_gc_lock while walking the LRU, but in the original code they release it before calling nfsd_file_dispose_list_delayed(). The fsnotify/lease path (nfsd_file_close_inode) has no synchronization at all.

Fix this by:

All operations inside the lock are non-sleeping (rhashtable lookups, atomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is appropriate.

Detalles técnicos trazas, registros y código del informe original
  1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan()
     to cover the nfsd_file_dispose_list_delayed() call.

  2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three
     callers of nfsd_file_dispose_list_delayed() hold the lock.

  3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in
     nfsd_file_cache_shutdown_net() after the purge, so that any
     in-progress disposal has fully completed before the per-net list
     is drained.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vector AV:N sin autenticación sugiere T1190, pero es parche de race condition en kernel sin vector claro de explotación remota. DoS por fuga de recursos (file leak) y corrupción potencial de estado en caché nfsd.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network TrafficVulnerability ScanningRestrict File and Directory PermissionsPrivileged Account ManagementRemote Data StorageNetwork Segmentation

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-89667",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.1,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 2.2
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "lessThan": "b15997b53b61c74fb4d083f7261d19f389ff854f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "lessThan": "6d6b9f6a75c3767250e9c23ace4e384ab8f7843e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "lessThan": "08af9593e2b472fd98c00faf1bf03bdbb7203477",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "lessThan": "40162cfea79b9510380decfdd1795b754dc9f972",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/nfsd/filecache.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.9",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/nfsd/filecache.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:53.177",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/08af9593e2b472fd98c00faf1bf03bdbb7203477",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/40162cfea79b9510380decfdd1795b754dc9f972",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6d6b9f6a75c3767250e9c23ace4e384ab8f7843e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b15997b53b61c74fb4d083f7261d19f389ff854f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache\n\nThe shrinker, GC worker, and fsnotify/lease callbacks can unhash an\nnfsd_file from the rhashtable and then call\nnfsd_file_dispose_list_delayed() to move it to the per-net dispose list.\nIf nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk\nmisses the already-unhashed file, and its drain of the per-net dispose\nlist can run before the file has been queued.  The file then sits on\nthe per-net list with no thread to drain it, leaking both the file and\nits associated state.\n\nThe GC worker and shrinker already hold nfsd_gc_lock while walking the\nLRU, but in the original code they release it before calling\nnfsd_file_dispose_list_delayed().  The fsnotify/lease path\n(nfsd_file_close_inode) has no synchronization at all.\n\nFix this by:\n\n  1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan()\n     to cover the nfsd_file_dispose_list_delayed() call.\n\n  2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three\n     callers of nfsd_file_dispose_list_delayed() hold the lock.\n\n  3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in\n     nfsd_file_cache_shutdown_net() after the purge, so that any\n     in-progress disposal has fully completed before the per-net list\n     is drained.\n\nAll operations inside the lock are non-sleeping (rhashtable lookups,\natomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is\nappropriate."
    }
  ],
  "lastModified": "2026-09-21T14:17:24.830",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}