CVE-2026-47066

Estado: AnalizadaAlta (8.7)—

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.

The entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.

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This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Puntuación base: 8.7

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.70%
Percentil entre todas las CVEs puntuadas: 52
Fecha de la puntuación: 6/10/2026

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.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1499.004 Application or System Exploitationimpact90 %

AV:N sin PR/UI permite exposición remota. El parser de Alt-Svc en HTTP es explotable por cualquier origen. El infinite loop que pina CPU 100% causa DoS (T1499.004 - Consumption de Recursos por Aplicación).

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 Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

Benoitc — Hackney

CWE

CWE-835

Referencias

JSON original (NVD)

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      "value": "Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.\n\nThe entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.0.1."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de bucle con condición de salida inalcanzable ('Bucle Infinito') en benoitc hackney permite asignación excesiva. El analizador de encabezados de respuesta Alt-Svc en src/hackney_altsvc.erl no garantiza el progreso hacia adelante. Cuando parse_token/2 recibe un byte que no es un token, no es un espacio en blanco, no es una coma (p. ej. '!', '@', '=', ';'), devuelve la entrada sin cambios. skip_comma/1 también devuelve el búfer sin cambios cuando el primer byte no es una coma. parse_entries/2 luego recurre con datos idénticos, creando un bucle recursivo de cola infinito y ajustado que fija un planificador al 100% de CPU. El proceso de llamada nunca regresa.\n\nEl punto de entrada parse_and_cache/3 se llama sincrónicamente en el proceso de conexión en cada respuesta HTTP. Un encabezado de respuesta Alt-Svc: '!' de un solo byte es suficiente para activar el bloqueo; el encabezado está totalmente controlado por cualquier origen HTTP al que se conecta el cliente.\n\nEste problema afecta a hackney: desde 2.0.0-beta.1 antes de 4.0.1."
    }
  ],
  "lastModified": "2026-07-24T10:10:00.197",
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