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CVE-2026-56766

Estado: AplazadaAlta (8.6)—

Hydra through 9.7, fixed in commit 9cc84c2, contains a stack buffer overflow in NTLM authentication across SMTP, POP3, IMAP, NNTP, HTTP, HTTP-Proxy, and HTTP-Proxy-Urlenum modules when processing malicious NTLM Type-2 challenges. A malicious server can send a crafted NTLM Type-2 challenge with an excessively long domain string, causing base64-encoded response data to overflow a 500-byte stack buffer by 18 to 330 bytes, enabling remote code execution on systems without stack protection.

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.

Buffer overflow en cliente NTLM (Hydra) al procesar respuesta maliciosa de servidor; requiere interacción del usuario (conexión SMTP/POP3/IMAP/etc.) y logra RCE sin privilegios previos.

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

Restrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationExecution PreventionBehavior Prevention on EndpointDisable or Remove Feature or Program

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Hydra — HydraAI

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2026-56766",
  "cveTags": [],
  "metrics": {
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        "ssvcData": {
          "id": "CVE-2026-56766",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-06-25T18:33:07.811052Z"
        }
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
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          "userInteraction": "REQUIRED",
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          "privilegesRequired": "NONE",
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      }
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    "cvssMetricV40": [
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        "type": "Secondary",
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          "Recovery": "NOT_DEFINED",
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          "valueDensity": "NOT_DEFINED",
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          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
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          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
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        {
          "repo": "https://github.com/vanhauser-thc/thc-hydra",
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            {
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  "published": "2026-06-25T19:16:43.577",
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    {
      "url": "https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2",
      "source": "disclosure@vulncheck.com"
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      "value": "Hydra through 9.7, fixed in commit 9cc84c2, contains a stack buffer overflow in NTLM authentication across SMTP, POP3, IMAP, NNTP, HTTP, HTTP-Proxy, and HTTP-Proxy-Urlenum modules when processing malicious NTLM Type-2 challenges. A malicious server can send a crafted NTLM Type-2 challenge with an excessively long domain string, causing base64-encoded response data to overflow a 500-byte stack buffer by 18 to 330 bytes, enabling remote code execution on systems without stack protection."
    }
  ],
  "lastModified": "2026-07-14T22:17:20.980",
  "sourceIdentifier": "disclosure@vulncheck.com"
}