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CVE-2026-33586

Estado: RecibidaMedia (6.3)—

Authenticated users are able to manipulate both the SMTP envelope “Envelope-from” and “From” fields when sending emails through OVH mail servers.

Due to OVH's default SPF configuration, which commonly includes include:mx.ovh.com, any authenticated user with a valid OVH email account can send messages that appear to originate from any OVH-hosted domains using the default SPF record. Since the SPF policy explicitly authorizes OVH mail servers (mx.ovh.com) to send mail on behalf of these domains, forged messages successfully pass SPF validation despite not being authorized by the impersonated domain owner.

CVSS

Probabilidad de explotación (EPSS)

FIRST aún no ha puntuado esta CVE (habitual en CVEs muy recientes o rechazadas).

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.

Autenticación requerida (PR:L) en servidores remotos OVH permite falsificar correos electrónicos abusando de SPF: phishing y fraude de email. CWE-290 (autenticación insuficiente) y CWE-346 (validación de origen incorrecta) sustentan suplantación de identidad en servidores de correo de red.

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

User TrainingSoftware ConfigurationVulnerability ScanningUser Account ManagementThreat Intelligence ProgramRestrict Web-Based Content

Tecnologías afectadas (1)

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

OVH — Mail ServersAI

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-33586",
  "cveTags": [],
  "metrics": {
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 6.3,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N/E:A/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",
          "exploitMaturity": "ATTACKED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "LOW",
          "subIntegrityImpact": "HIGH",
          "vulnIntegrityImpact": "NONE",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
      "affectedData": [
        {
          "vendor": "OVHcloud",
          "product": "OVHcloud",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "2026-07-20",
              "versionType": "date"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-10-07T16:17:47.643",
  "references": [
    {
      "url": "https://docs.ovhcloud.com/en/guides/web-cloud/email-and-collaborative-solutions/troubleshooting/email-rejected-cross-domain-spoofing",
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158"
    }
  ],
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
      "description": [
        {
          "lang": "en",
          "value": "CWE-290"
        },
        {
          "lang": "en",
          "value": "CWE-346"
        },
        {
          "lang": "en",
          "value": "CWE-1188"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Authenticated users are able to manipulate both the SMTP\nenvelope “Envelope-from” and “From” fields when sending\nemails through OVH mail servers.\n\n\n\nDue to OVH's default SPF configuration, which\ncommonly includes include:mx.ovh.com, any authenticated user with a\nvalid OVH email account can send messages that appear to originate from any\nOVH-hosted domains using the default SPF record. Since the SPF policy\nexplicitly authorizes OVH mail servers (mx.ovh.com) to send mail on behalf of\nthese domains, forged messages successfully pass SPF validation despite\nnot being authorized by the impersonated domain owner."
    }
  ],
  "lastModified": "2026-10-07T16:17:47.643",
  "sourceIdentifier": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158"
}