CVE-2026-89663

Estado: RecibidaAlta (8.8)—

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

nfsd: revoke copy-notify stateids before dropping their reference

Copy-notify stateids live in the s2s_cp_stateids IDR and on their parent stid's sc_cp_list, pinned by a single membership reference. _free_cpntf_state_locked() only unlinks an entry once its refcount reaches zero, so any revoke path that runs while a concurrent find_cpntf_state()/manage_cpntf_state() holder has elevated cs_count drops the reference without unlinking, leaving the entry discoverable with its membership reference already consumed. A second revoke or a laundromat tick then frees it while the reader still holds the pointer -- a KASAN-detectable use-after-free at the reader's nfs4_put_cpntf_state().

Leer descripción completaMostrar menos

This affected all three revoke paths:

Add revoke_cpntf_state_locked(), which unhashes the entry from the IDR and sc_cp_list first (deferring the final free to any holder), and use it from all three revoke paths. The drain now walks with list_for_each_entry_safe() and revokes each entry unconditionally, so it terminates in one pass per entry regardless of cs_count. The unhash is gated on !list_empty(&cps->cp_list); the idr_remove() gate matters because idr_alloc_cyclic() may have recycled the so_id by then. Keep _free_cpntf_state_locked() for the reference-holder put path only, where a concurrent revoke may already have unlinked the entry (its list_del_init() then a no-op).

Detalles técnicos trazas, registros y código del informe original

  - The parent-stid drain (nfs4_free_cpntf_statelist()) repeatedly called
    _free_cpntf_state_locked() on the first list entry; a holder that had
    bumped cs_count made it return early, so the next iteration
    re-decremented and burned the holder's reference.

  - OFFLOAD_CANCEL (manage_cpntf_state()) and laundromat expiry likewise
    used _free_cpntf_state_locked() and could drop 2->1 without unlinking.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 8.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.46%
Percentil entre todas las CVEs puntuadas: 37
Fecha de la puntuación: 6/10/2026

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.

ExplotaciónT1210 Exploitation of Remote Serviceslateral movement75 %
Impacto principalT1499.004 Application or System Exploitationimpact65 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact60 %

Vulnerabilidad en kernel Linux que permite DoS por use-after-free en nfsd (acceso red con privilegios PR:L). La carrera de referencias puede causar caída del servicio o corrupción de datos en memoria compartida.

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

Vulnerability Scanning Threat Intelligence Program Restrict File and Directory Permissions Privileged Account Management Remote Data Storage Network 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 Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-89663",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.8,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 2.8
      }
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  "affected": [
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      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "status": "affected",
              "version": "624322f1adc58acd0b69f77a6ddc764207e97241",
              "lessThan": "5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d",
              "versionType": "git"
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              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3",
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              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "624322f1adc58acd0b69f77a6ddc764207e97241",
              "lessThan": "b56d2c5f01cddbeca7d11cce81d97db4ec9a464f",
              "versionType": "git"
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            {
              "status": "affected",
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              "lessThan": "3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.6"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.6",
              "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-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:52.653",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/06a62f6dbc60791f4229c6950b1eec6b18df9af1",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6b8149448cdcb476fba4559d1ecc247efee9971b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/caddbeffab1eaba1d2bcf5ceda35547863466705",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ff8a3cff02b92b2a82f1a9876038fcf953ae9c25",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: revoke copy-notify stateids before dropping their reference\n\nCopy-notify stateids live in the s2s_cp_stateids IDR and on their parent\nstid's sc_cp_list, pinned by a single membership reference.\n_free_cpntf_state_locked() only unlinks an entry once its refcount reaches\nzero, so any revoke path that runs while a concurrent\nfind_cpntf_state()/manage_cpntf_state() holder has elevated cs_count drops\nthe reference without unlinking, leaving the entry discoverable with its\nmembership reference already consumed. A second revoke or a laundromat tick\nthen frees it while the reader still holds the pointer -- a\nKASAN-detectable use-after-free at the reader's nfs4_put_cpntf_state().\n\nThis affected all three revoke paths:\n\n  - The parent-stid drain (nfs4_free_cpntf_statelist()) repeatedly called\n    _free_cpntf_state_locked() on the first list entry; a holder that had\n    bumped cs_count made it return early, so the next iteration\n    re-decremented and burned the holder's reference.\n\n  - OFFLOAD_CANCEL (manage_cpntf_state()) and laundromat expiry likewise\n    used _free_cpntf_state_locked() and could drop 2->1 without unlinking.\n\nAdd revoke_cpntf_state_locked(), which unhashes the entry from the IDR and\nsc_cp_list first (deferring the final free to any holder), and use it from\nall three revoke paths. The drain now walks with list_for_each_entry_safe()\nand revokes each entry unconditionally, so it terminates in one pass per\nentry regardless of cs_count. The unhash is gated on\n!list_empty(&cps->cp_list); the idr_remove() gate matters because\nidr_alloc_cyclic() may have recycled the so_id by then. Keep\n_free_cpntf_state_locked() for the reference-holder put path only, where a\nconcurrent revoke may already have unlinked the entry (its list_del_init()\nthen a no-op)."
    }
  ],
  "lastModified": "2026-09-14T13:19:18.533",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}