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CVE-2026-55203

Estado: AnalizadaCrítica (9)—

HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.

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.

Vulnerabilidad de desbordamiento entero en HAProxy accesible remotamente sin autenticación (AV:N, PR:N). Permite desincronización del parser FCGI causando ejecución de código, manipulación de datos y enrutamiento incorrecto de solicitudes.

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

Privileged Account ManagementNetwork SegmentationFilter Network TrafficVulnerability ScanningSSL/TLS InspectionRestrict Web-Based Content

Tecnologías afectadas (1)

Haproxy — Haproxy

CWE

Referencias

JSON original (NVD)

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    }
  ],
  "lastModified": "2026-07-14T22:17:17.570",
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