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CVE-2024-56828

Estado: AnalizadaCrítica (9.8)—

File Upload vulnerability in ChestnutCMS through 1.5.0. Based on the code analysis, it was determined that the /api/member/avatar API endpoint receives a base64 string as input. This string is then passed to the memberService.uploadAvatarByBase64 method for processing. Within the service, the base64-encoded image is parsed. For example, given a string like: data:image/html;base64,PGh0bWw+PGltZyBzcmM9eCBvbmVycm9yPWFsZXJ0KDEpPjwvaHRtbD4= the content after the comma is extracted and decoded using Base64.getDecoder().decode().

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The substring from the 11th character up to the first occurrence of a semicolon (;) is assigned to the suffix variable (representing the file extension). The decoded content is then written to a file. However, the file extension is not validated, and since this functionality is exposed to the frontend, it poses significant security risks.

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.

AV:N/AC:L/PR:N: red sin autenticación. Carga de archivo sin validación en endpoint /api/member/avatar permite crear web shell mediante base64. T1505.003 por persistencia web; T1059 por ejecución de código implícita en shell.

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 ScanningUser Account ManagementRestrict Web-Based ContentNetwork Segmentation

Tecnologías afectadas (1)

1000mz — Chestnutcms

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2024-56828",
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          "id": "CVE-2024-56828",
          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "poc"
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            {
              "automatable": "yes"
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            {
              "technicalImpact": "total"
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          "version": "2.0.3",
          "timestamp": "2025-01-14T20:47:43.963032Z"
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
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  "published": "2025-01-06T18:15:23.467",
  "references": [
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      "url": "https://gitee.com/liweiyi/ChestnutCMS",
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  "descriptions": [
    {
      "lang": "en",
      "value": "File Upload vulnerability in ChestnutCMS through 1.5.0. Based on the code analysis, it was determined that the /api/member/avatar API endpoint receives a base64 string as input. This string is then passed to the memberService.uploadAvatarByBase64 method for processing. Within the service, the base64-encoded image is parsed. For example, given a string like: data:image/html;base64,PGh0bWw+PGltZyBzcmM9eCBvbmVycm9yPWFsZXJ0KDEpPjwvaHRtbD4= the content after the comma is extracted and decoded using Base64.getDecoder().decode(). The substring from the 11th character up to the first occurrence of a semicolon (;) is assigned to the suffix variable (representing the file extension). The decoded content is then written to a file. However, the file extension is not validated, and since this functionality is exposed to the frontend, it poses significant security risks."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de carga de archivos en ChestnutCMS hasta la versión 1.5.0. Según el análisis del código, se determinó que el endpoint de la API /api/member/avatar recibe una cadena base64 como entrada. Esta cadena se pasa luego al método memberService.uploadAvatarByBase64 para su procesamiento. Dentro del servicio, se analiza la imagen codificada en base64. Por ejemplo, dada una cadena como: data:image/html;base64,PGh0bWw+PGltZyBzcmM9eCBvbmVycm9yPWFsZXJ0KDEpPjwvaHRtbD4= el contenido después de la coma se extrae y se decodifica utilizando Base64.getDecoder().decode(). La subcadena desde el undécimo carácter hasta la primera aparición de un punto y coma (;) se asigna a la variable de sufijo (que representa la extensión del archivo). Luego, el contenido decodificado se escribe en un archivo. Sin embargo, la extensión del archivo no está validada y, dado que esta funcionalidad está expuesta al frontend, plantea riesgos de seguridad importantes."
    }
  ],
  "lastModified": "2026-06-17T08:13:01.600",
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  "sourceIdentifier": "cve@mitre.org"
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