CVE-2026-9771

{
  "id": "CVE-2026-9771",
  "sourceIdentifier": "[email protected]",
  "published": "2026-08-17T17:16:57.720",
  "lastModified": "2026-10-23T16:10:00.313",
  "vulnStatus": "Awaiting Analysis",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The flash_copy() system call is verified by z_vrfy_flash_copy() in drivers/flash/flash_util.c. On builds with CONFIG_USERSPACE enabled, this handler is the kernel-side trust boundary for a user-mode caller. Prior to the fix it validated only the output buffer (K_SYSCALL_MEMORY_WRITE) and passed the two struct device * arguments, src_dev and dst_dev, directly into the implementation without any object validation — unlike every sibling flash syscall, which guards its device pointer with K_SYSCALL_DRIVER_FLASH.\n\nA user-mode thread fully controls the values of src_dev/dst_dev and the contents of its own address space. The implementation z_impl_flash_copy() dereferences these pointers and calls through their driver-API function tables (e.g. api->get_parameters(dst_dev), flash_read(src_dev, ...), flash_write(dst_dev, ...)). By supplying a pointer to a forged struct device whose api table contains attacker-chosen function pointers, an unprivileged thread can cause the kernel to call arbitrary code in supervisor mode; passing any arbitrary or invalid address otherwise yields a kernel crash or out-of-bounds read.\n\nThe result is a local privilege escalation out of the userspace sandbox (with kernel denial-of-service and information disclosure as lesser outcomes). The fix adds K_SYSCALL_DRIVER_FLASH(src_dev, read) and K_SYSCALL_DRIVER_FLASH(dst_dev, write) to z_vrfy_flash_copy(), which verify each device is a registered flash-driver kernel object the calling thread is permitted to use before any dereference, closing the path completely."
    },
    {
      "lang": "es",
      "value": "La llamada al sistema flash_copy() es verificada por z_vrfy_flash_copy() en drivers/flash/flash_util.c. En compilaciones con CONFIG_USERSPACE habilitado, este gestor es el límite de confianza del lado del kernel para un llamador en modo usuario. Antes de la corrección, solo validaba el búfer de salida (K_SYSCALL_MEMORY_WRITE) y pasaba los dos argumentos de tipo struct device *, src_dev y dst_dev, directamente a la implementación sin ninguna validación de objeto - a diferencia de cada llamada al sistema flash hermana, que protege su puntero de dispositivo con K_SYSCALL_DRIVER_FLASH.\n\nUn hilo en modo usuario controla completamente los valores de src_dev/dst_dev y el contenido de su propio espacio de direcciones. La implementación z_impl_flash_copy() desreferencia estos punteros y realiza llamadas a través de sus tablas de funciones de la API del controlador (p. ej., api  ->  get_parameters(dst_dev), flash_read(src_dev, ...), flash_write(dst_dev, ...)). Al proporcionar un puntero a una struct device falsificada cuya tabla de la API contiene punteros a funciones elegidos por el atacante, un hilo sin privilegios puede hacer que el kernel llame a código arbitrario en modo supervisor; pasar cualquier dirección arbitraria o inválida de otro modo produce un fallo del kernel o una lectura fuera de límites.\n\nEl resultado es una escalada de privilegios local fuera de la sandbox del espacio de usuario (con denegación de servicio del kernel y revelación de información como resultados menores). La corrección añade K_SYSCALL_DRIVER_FLASH(src_dev, read) y K_SYSCALL_DRIVER_FLASH(dst_dev, write) a z_vrfy_flash_copy(), que verifican que cada dispositivo es un objeto del kernel de controlador flash registrado que el hilo llamador tiene permiso para usar antes de cualquier desreferencia, cerrando la ruta por completo."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "zephyrproject",
          "product": "zephyr",
          "defaultStatus": "unaffected",
          "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
          "packageName": "zephyr",
          "programFiles": [
            "drivers/flash/flash_util.c"
          ],
          "versions": [
            {
              "version": "4.0.0",
              "lessThan": "4.4.2",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "CHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.0,
        "impactScore": 6.0
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-17T18:24:21.736349Z",
          "id": "CVE-2026-9771",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-822"
        },
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/zephyrproject-rtos/zephyr/commit/1b1ecdc438092cdd469319a0d51cba6cf82e06f4",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-68cj-3hg4-5vpm",
      "source": "[email protected]"
    }
  ]
}