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CVE-2026-25539

Estado: AnalizadaAlta (7.2)—

SiYuan is a personal knowledge management system. Prior to version 3.5.5, the /api/file/copyFile endpoint does not validate the dest parameter, allowing authenticated users to write files to arbitrary locations on the filesystem. This can lead to Remote Code Execution (RCE) by writing to sensitive locations such as cron jobs, SSH authorized_keys, or shell configuration files. This issue has been patched in version 3.5.5.

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.

Acceso red con PR:H (autenticado) a endpoint sin validación permite escritura arbitraria en filesystem y RCE; técnica padre T1059 por ejecución de código indeterminada en el servidor.

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 ManagementDisable or Remove Feature or ProgramVulnerability ScanningThreat Intelligence ProgramRestrict Web-Based ContentNetwork Segmentation

Tecnologías afectadas (1)

B3log — Siyuan

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-25539",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-25539",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-02-05T18:32:24.271345Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 9.1,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "HIGH",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 6,
        "exploitabilityScore": 2.3
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.2,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
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          "availabilityImpact": "HIGH",
          "privilegesRequired": "HIGH",
          "confidentialityImpact": "HIGH"
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      }
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          "product": "siyuan",
          "versions": [
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              "version": "< 3.5.5"
            }
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  "published": "2026-02-04T22:16:00.083",
  "references": [
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      "url": "https://github.com/siyuan-note/siyuan/commit/d7f790755edf8c78d2b4176171e5a0cdcd720feb",
      "tags": [
        "Patch"
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      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9",
      "tags": [
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        "Vendor Advisory"
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      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9",
      "tags": [
        "Exploit",
        "Vendor Advisory"
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
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  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "SiYuan is a personal knowledge management system. Prior to version 3.5.5, the /api/file/copyFile endpoint does not validate the dest parameter, allowing authenticated users to write files to arbitrary locations on the filesystem. This can lead to Remote Code Execution (RCE) by writing to sensitive locations such as cron jobs, SSH authorized_keys, or shell configuration files. This issue has been patched in version 3.5.5."
    },
    {
      "lang": "es",
      "value": "SiYuan es un sistema de gestión de conocimiento personal. Antes de la versión 3.5.5, el endpoint /api/file/copyFile no valida el parámetro dest, permitiendo a usuarios autenticados escribir archivos en ubicaciones arbitrarias en el sistema de archivos. Esto puede llevar a la Ejecución Remota de Código (RCE) al escribir en ubicaciones sensibles como trabajos cron, SSH authorized_keys o archivos de configuración de shell. Este problema ha sido parcheado en la versión 3.5.5."
    }
  ],
  "lastModified": "2026-06-17T10:24:49.180",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "vulnerable": true,
              "matchCriteriaId": "3141D3B1-ED56-4898-B115-8863570D1D63",
              "versionEndIncluding": "3.5.3"
            }
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          "operator": "OR"
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  "sourceIdentifier": "security-advisories@github.com"
}