CVE-2026-71254

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "nanoMODBUS", "programFiles": ["nanomodbus.c"], "vendor": "debevv", "versions": [{"lessThanOrEqual": "1.23.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus server-side handle_read_file_record function (FC 0x14, Read File Record) in nanomodbus.c. The function validates that the total request size does not exceed 245 bytes and that each sub-request's record_length is at most 124, but it never validates the CUMULATIVE response size across all sub-requests before processing them."}, {"lang": "es", "value": "nanoMODBUS hasta la v1.23.0 contiene una escritura fuera de l\u00edmites en la funci\u00f3n handle_read_file_record() del lado del servidor Modbus (FC 0x14, Lectura de Registro de Archivo) en nanomodbus.c. La funci\u00f3n valida que el tama\u00f1o total de la solicitud no exceda los 245 bytes y que la record_length de cada sub-solicitud sea como m\u00e1ximo 124, pero nunca valida el tama\u00f1o de respuesta ACUMULATIVO de todas las sub-solicitudes antes de procesarlas. El acumulador response_data_size se declara como uint8_t y se incrementa en 2 + record_length2 por cada una de hasta 35 sub-solicitudes; con 35 sub-solicitudes de record_length=124, la demanda acumulada es de 8750 bytes, lo que desborda el acumulador uint8_t. Un bucle posterior llama entonces a get_n(), una funci\u00f3n interna sin comprobaci\u00f3n de l\u00edmites, una vez por sub-solicitud para obtener un puntero al b\u00fafer de recepci\u00f3n msg.buf de 260 bytes y avanza el buf_idx interno hasta 248 bytes por llamada; swap_regs() luego escribe en ese puntero incondicionalmente. Una \u00fanica solicitud FC 0x14 manipulada de un cliente de red no autenticado puede causar que se escriban hasta ~8490 bytes fuera de los l\u00edmites m\u00e1s all\u00e1 del b\u00fafer de 260 bytes, corrompiendo la memoria adyacente en el proceso del servidor y llevando a denegaci\u00f3n de servicio o potencial ejecuci\u00f3n remota de c\u00f3digo, particularmente en objetivos embebidos/bare-metal sin protecci\u00f3n de memoria."}], "id": "CVE-2026-71254", "lastModified": "2026-10-24T15:10:00.190", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-71254", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-08-05T12:29:36.579901Z", "version": "2.0.3"}}]}, "published": "2026-08-05T12:18:57.600", "references": [{"source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "url": "https://github.com/debevv/nanoMODBUS"}, {"source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c"}], "sourceIdentifier": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "type": "Secondary"}]}

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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,1.23.0]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "nanoMODBUS", "source": "cna", "vendor": "debevv"}, "product": "nanomodbus", "vendor": "debevv"}], "created": "2026-08-05T13:30:04.917215+00:00", "updated": "2026-08-10T23:00:07.492251+00:00", "vendors": ["debevv", "debevv$PRODUCT$nanomodbus"]}