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CVE-2026-45352

Estado: ModificadaAlta (7.5)—

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul("-2", …, 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE).

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The library's only guard (line 12833) rejects ULONG_MAX (the result of "-1"), but any other negative value such as "-2" passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server's read loop consumes from the network. This vulnerability is fixed in 0.43.4.

CVSS

Probabilidad de explotación (EPSS)

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.

AV:N/PR:N/UI:N indica explotación remota sin autenticación (T1190). Desbordamiento de memoria por chunk negativo causa denegación de servicio (T1499.004).

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

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Tecnologías afectadas (1)

Yhirose — Cpp-httplib

CWE

Referencias

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      "value": "cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul(\"-2\", …, 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE). The library's only guard (line 12833) rejects ULONG_MAX (the result of \"-1\"), but any other negative value such as \"-2\" passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server's read loop consumes from the network. This vulnerability is fixed in 0.43.4."
    },
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      "lang": "es",
      "value": "cpp-httplib es una biblioteca HTTP/HTTPS multiplataforma de C++11 de un solo archivo de solo encabezado. Antes de la 0.43.4, un tamaño de fragmento negativo en la codificación de transferencia fragmentada (chunked Transfer-Encoding) causa una asignación de memoria ilimitada y la caída del proceso. La función ChunkedDecoder::read_payload en cpp-httplib (httplib.h) analiza el campo de tamaño de fragmento de la codificación de transferencia fragmentada HTTP utilizando std::strtoul(). Según el estándar C (§7.22.1.4), strtoul acepta silenciosamente un signo menos inicial, realizando un desbordamiento sin signo: strtoul('-2', ..., 16) devuelve ULONG_MAX ? 1 (0xFFFFFFFFFFFFFFFE). La única protección de la biblioteca (línea 12833) rechaza ULONG_MAX (el resultado de '-1'), pero cualquier otro valor negativo como '-2' pasa la validación. El valor casi máximo resultante se almacena en chunk_remaining y controla cuántos bytes el bucle de lectura del servidor consume de la red. Esta vulnerabilidad está corregida en la 0.43.4."
    }
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  "lastModified": "2026-07-22T06:10:00.170",
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