CVE-2026-71256

{
  "id": "CVE-2026-71256",
  "sourceIdentifier": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
  "published": "2026-08-05T12:18:57.847",
  "lastModified": "2026-10-24T15:10:00.190",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "nanoMODBUS through v1.23.0 contains an out-of-bounds stack read leading to a wild-pointer write in nmbs_read_device_identification_basic / recv_read_device_identification_res in nanomodbus.c. A fixed 3-element stack array order[3] = {0,1,2} maps object IDs to buffer indices. The server-supplied object_id field (0-255, read directly from the wire) is used without any bounds check as buf_index = order[object_id]."
    },
    {
      "lang": "es",
      "value": "nanoMODBUS hasta la v1.23.0 contiene una lectura de pila fuera de límites que lleva a una escritura de puntero salvaje en nmbs_read_device_identification_basic() / recv_read_device_identification_res() en nanomodbus.c. Un array de pila fijo de 3 elementos order[3] = {0,1,2} mapea IDs de objeto a índices de búfer. El campo object_id proporcionado por el servidor (0-255, leído directamente del cable) se utiliza sin ninguna comprobación de límites como buf_index = order[object_id]. Cuando un servidor Modbus malicioso envía una respuesta de Identificación de Dispositivo de Lectura con object_id mayor o igual que 3, esto lee un byte fuera de límites/basura de la pila adyacente a order[], que luego se utiliza como un índice en un array buffers[] de 3 elementos de punteros char. El puntero salvaje resultante se pasa a strncpy() como destino, causando una escritura de dirección arbitraria con datos controlados por el servidor."
    }
  ],
  "affected": [
    {
      "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
      "affectedData": [
        {
          "vendor": "debevv",
          "product": "nanoMODBUS",
          "defaultStatus": "unaffected",
          "programFiles": [
            "nanomodbus.c"
          ],
          "versions": [
            {
              "version": "0",
              "lessThanOrEqual": "1.23.0",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
        "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": "2026-08-05T12:25:23.617290Z",
          "id": "CVE-2026-71256",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/debevv/nanoMODBUS",
      "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c"
    },
    {
      "url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c",
      "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c"
    }
  ]
}