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CVE-2026-45116

Estado: AplazadaAlta (8.7)—

MyBB is free and open source forum software. Prior to 1.8.40, the user datahandler does not properly validate checkbox and multiselect profile field types, resulting in stored JavaScript code injection. UserDataHandler::verify_profile_fields() only performs the specialized validation when is_array($profile_fields[$field]) is true. A non-array profile_fields[fidX] value instead of the expected profile_fields[fidX][] shape falls through to generic text handling and is stored without verification. The affected value is then rendered directly by member.php and inc/functions_post.php rather than processed by the MyCode parser. The uniquely identifying implementation details include inc/datahandlers/user.php. This issue is fixed in version 1.8.40.

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.

XSS almacenado (CWE-79) en campos de perfil de MyBB renderizado sin sanitización (T1189). Inyección JS ejecutada en navegador (T1059.007) y posible secuestro de sesiones/cuentas (T1098.002) mediante robo de cookies de autenticación.

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 ContentDisable or Remove Feature or ProgramUser TrainingPrivileged Account ManagementMulti-factor AuthenticationExecution Prevention

Tecnologías afectadas (1)

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

Mybb — MybbAI

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-45116",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-45116",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-08-18T17:55:09.371549Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 8.7,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.8,
        "exploitabilityScore": 2.3
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "mybb",
          "product": "mybb",
          "versions": [
            {
              "status": "affected",
              "version": "< 1.8.40"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-08-18T16:17:06.347",
  "references": [
    {
      "url": "https://github.com/mybb/mybb/commit/c32f0c22baab704a68b8d58fcdd2f26fadbbe19b",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/mybb/mybb/releases/tag/mybb_1840",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/mybb/mybb/security/advisories/GHSA-4p6g-p3qh-559v",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://mybb.com/versions/1.8.40",
      "source": "security-advisories@github.com"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "MyBB is free and open source forum software. Prior to 1.8.40, the user datahandler does not properly validate checkbox and multiselect profile field types, resulting in stored JavaScript code injection. UserDataHandler::verify_profile_fields() only performs the specialized validation when is_array($profile_fields[$field]) is true. A non-array profile_fields[fidX] value instead of the expected profile_fields[fidX][] shape falls through to generic text handling and is stored without verification. The affected value is then rendered directly by member.php and inc/functions_post.php rather than processed by the MyCode parser. The uniquely identifying implementation details include inc/datahandlers/user.php. This issue is fixed in version 1.8.40."
    }
  ],
  "lastModified": "2026-09-08T21:02:26.047",
  "sourceIdentifier": "security-advisories@github.com"
}