CVE-2025-71070

Estado: AplazadaAlta (7.8)—

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

ublk: clean up user copy references on ublk server exit

If a ublk server process releases a ublk char device file, any requests dispatched to the ublk server but not yet completed will retain a ref value of UBLK_REFCOUNT_INIT. Before commit e63d2228ef83 ("ublk: simplify aborting ublk request"), __ublk_fail_req() would decrement the reference count before completing the failed request. However, that commit optimized __ublk_fail_req() to call __ublk_complete_rq() directly without decrementing the request reference count.

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The leaked reference count incorrectly allows user copy and zero copy operations on the completed ublk request. It also triggers the WARN_ON_ONCE(refcount_read(&io->ref)) warnings in ublk_queue_reinit() and ublk_deinit_queue(). Commit c5c5eb24ed61 ("ublk: avoid ublk_io_release() called after ublk char dev is closed") already fixed the issue for ublk devices using UBLK_F_SUPPORT_ZERO_COPY or UBLK_F_AUTO_BUF_REG. However, the reference count leak also affects UBLK_F_USER_COPY, the other reference-counted data copy mode. Fix the condition in ublk_check_and_reset_active_ref() to include all reference-counted data copy modes. This ensures that any ublk requests still owned by the ublk server when it exits have their reference counts reset to 0.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.14%
Percentil entre todas las CVEs puntuadas: 3
Fecha de la puntuación: 4/10/2026

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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1059 Command and Scripting Interpreterexecution70 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact65 %

AV:L/PR:L permite escalada local; fuga de referencias permite ejecución de código y manipulación de datos en operaciones de copia en kernel ublk.

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

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Restrict File and Directory Permissions Privileged Account Management Remote Data Storage

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-2025-71070",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/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": 1.8
      }
    ]
  },
  "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": "e63d2228ef831af36f963b3ab8604160cfff84c1",
              "lessThan": "13456b4f1033d911f8bf3a0a1195656f293ba0f6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e63d2228ef831af36f963b3ab8604160cfff84c1",
              "lessThan": "daa24603d9f0808929514ee62ced30052ca7221c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e537193fc4a43b48ac51cc6366319e15e32dd540",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6.14.6",
              "lessThan": "6.15",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "drivers/block/ublk_drv.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.15",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.3",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/block/ublk_drv.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-01-13T16:16:06.413",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/13456b4f1033d911f8bf3a0a1195656f293ba0f6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/daa24603d9f0808929514ee62ced30052ca7221c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Deferred",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: clean up user copy references on ublk server exit\n\nIf a ublk server process releases a ublk char device file, any requests\ndispatched to the ublk server but not yet completed will retain a ref\nvalue of UBLK_REFCOUNT_INIT. Before commit e63d2228ef83 (\"ublk: simplify\naborting ublk request\"), __ublk_fail_req() would decrement the reference\ncount before completing the failed request. However, that commit\noptimized __ublk_fail_req() to call __ublk_complete_rq() directly\nwithout decrementing the request reference count.\nThe leaked reference count incorrectly allows user copy and zero copy\noperations on the completed ublk request. It also triggers the\nWARN_ON_ONCE(refcount_read(&io->ref)) warnings in ublk_queue_reinit()\nand ublk_deinit_queue().\nCommit c5c5eb24ed61 (\"ublk: avoid ublk_io_release() called after ublk\nchar dev is closed\") already fixed the issue for ublk devices using\nUBLK_F_SUPPORT_ZERO_COPY or UBLK_F_AUTO_BUF_REG. However, the reference\ncount leak also affects UBLK_F_USER_COPY, the other reference-counted\ndata copy mode. Fix the condition in ublk_check_and_reset_active_ref()\nto include all reference-counted data copy modes. This ensures that any\nublk requests still owned by the ublk server when it exits have their\nreference counts reset to 0."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nublk: limpiar referencias de copia de usuario al salir el servidor ublk\n\nSi un proceso de servidor ublk libera un archivo de dispositivo de caracteres ublk, cualquier solicitud despachada al servidor ublk pero aún no completada retendrá un valor de referencia de UBLK_REFCOUNT_INIT. Antes del commit e63d2228ef83 ('ublk: simplificar la anulación de solicitud ublk'), __ublk_fail_req() decrementaría el contador de referencias antes de completar la solicitud fallida. Sin embargo, ese commit optimizó __ublk_fail_req() para llamar directamente a __ublk_complete_rq() sin decrementar el contador de referencias de la solicitud.\nEl contador de referencias filtrado permite incorrectamente operaciones de copia de usuario y copia cero en la solicitud ublk completada. También activa las advertencias WARN_ON_ONCE(refcount_read(&amp;io-&gt;ref)) en ublk_queue_reinit() y ublk_deinit_queue().\nEl commit c5c5eb24ed61 ('ublk: evitar que se llame a ublk_io_release() después de cerrar el dispositivo de caracteres ublk') ya solucionó el problema para dispositivos ublk que utilizan UBLK_F_SUPPORT_ZERO_COPY o UBLK_F_AUTO_BUF_REG. Sin embargo, la fuga del contador de referencias también afecta a UBLK_F_USER_COPY, el otro modo de copia de datos con contador de referencias. Corregir la condición en ublk_check_and_reset_active_ref() para incluir todos los modos de copia de datos con contador de referencias. Esto asegura que cualquier solicitud ublk aún propiedad del servidor ublk cuando este sale tenga sus contadores de referencias restablecidos a 0."
    }
  ],
  "lastModified": "2026-07-30T06:24:48.753",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}