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CVE-2026-34401

Estado: AnalizadaMedia (6.5)—

XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents. Prior to version 2.9.0.21, XML Notepad does not disable DTD processing by default which means external entities are resolved automatically. There is a well known attack related to malicious DTD files where an attacker to craft a malicious XML file that loads a DTD that causes XML Notepad to make outbound HTTP/SMB requests, potentially leaking local file contents or capturing the victim's NTLM credentials. This issue has been patched in version 2.9.0.21.

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).

Tecnologías afectadas (1)

Microsoft — XML Notepad

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-34401",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-34401",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-04-01T15:45:24.184266Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.5,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "microsoft",
          "product": "XmlNotepad",
          "versions": [
            {
              "status": "affected",
              "version": "< 2.9.0.21"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-03-31T22:16:18.490",
  "references": [
    {
      "url": "https://github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140c",
      "tags": [
        "Patch"
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      "url": "https://github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53",
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      "tags": [
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        "Release Notes"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-611"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents. Prior to version 2.9.0.21, XML Notepad does not disable DTD processing by default which means external entities are resolved automatically. There is a well known attack related to malicious DTD files where an attacker to craft a malicious XML file that loads a DTD that causes XML Notepad to make outbound HTTP/SMB requests, potentially leaking local file contents or capturing the victim's NTLM credentials. This issue has been patched in version 2.9.0.21."
    },
    {
      "lang": "es",
      "value": "XML Notepad es un programa de Windows que proporciona una interfaz de usuario sencilla e intuitiva para navegar y editar documentos XML. Antes de la versión 2.9.0.21, XML Notepad no deshabilita el procesamiento de DTD por defecto, lo que significa que las entidades externas se resuelven automáticamente. Existe un ataque bien conocido relacionado con archivos DTD maliciosos donde un atacante puede crear un archivo XML malicioso que carga un DTD que hace que XML Notepad realice solicitudes HTTP/SMB salientes, potencialmente filtrando el contenido de archivos locales o capturando las credenciales NTLM de la víctima. Este problema ha sido parcheado en la versión 2.9.0.21."
    }
  ],
  "lastModified": "2026-07-24T21:10:00.143",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:microsoft:xml_notepad:*:*:*:*:*:windows:*:*",
              "vulnerable": true,
              "matchCriteriaId": "F08C7164-A566-4527-8764-F9BC54E164F1",
              "versionEndExcluding": "2.9.0.21"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security-advisories@github.com"
}