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CVE-2021-29460

Status: ModifiedMedium (5.4)—💥 Exploit

Kirby is an open source CMS. An editor with write access to the Kirby Panel can upload an SVG file that contains harmful content like `<script>` tags. The direct link to that file can be sent to other users or visitors of the site. If the victim opens that link in a browser where they are logged in to Kirby, the script will run and can for example trigger requests to Kirby's API with the permissions of the victim.

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This vulnerability is critical if you might have potential attackers in your group of authenticated Panel users, as they can escalate their privileges if they get access to the Panel session of an admin user. Depending on your site, other JavaScript-powered attacks are possible. Visitors without Panel access can only use this attack vector if your site allows SVG file uploads in frontend forms and you don't already sanitize uploaded SVG files. The problem has been patched in Kirby 3.5.4. Please update to this or a later version to fix the vulnerability. Frontend upload forms need to be patched separately depending on how they store the uploaded file(s). If you use `File::create()`, you are protected by updating to 3.5.4+. As a work around you can disable the upload of SVG files in your file blueprints.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

💥 Public exploits

Exploit code or detection templates are publicly available. This is not the same as confirmed active exploitation (KEV), but it raises the risk: patch with priority.

Affected technologies (1)

Getkirby — Kirby

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-29460",
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          "vectorString": "AV:N/AC:M/Au:S/C:N/I:P/A:N",
          "authentication": "SINGLE",
          "integrityImpact": "PARTIAL",
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  "published": "2021-04-27T20:15:08.860",
  "references": [
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      "url": "http://packetstormsecurity.com/files/162359/Kirby-CMS-3.5.3.1-Cross-Site-Scripting.html",
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  "vulnStatus": "Modified",
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      "description": [
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    {
      "lang": "en",
      "value": "Kirby is an open source CMS. An editor with write access to the Kirby Panel can upload an SVG file that contains harmful content like `<script>` tags. The direct link to that file can be sent to other users or visitors of the site. If the victim opens that link in a browser where they are logged in to Kirby, the script will run and can for example trigger requests to Kirby's API with the permissions of the victim. This vulnerability is critical if you might have potential attackers in your group of authenticated Panel users, as they can escalate their privileges if they get access to the Panel session of an admin user. Depending on your site, other JavaScript-powered attacks are possible. Visitors without Panel access can only use this attack vector if your site allows SVG file uploads in frontend forms and you don't already sanitize uploaded SVG files. The problem has been patched in Kirby 3.5.4. Please update to this or a later version to fix the vulnerability. Frontend upload forms need to be patched separately depending on how they store the uploaded file(s). If you use `File::create()`, you are protected by updating to 3.5.4+. As a work around you can disable the upload of SVG files in your file blueprints."
    },
    {
      "lang": "es",
      "value": "Kirby es un CMS de código abierto.&#xa0;Un editor con acceso de escritura al Kirby Panel puede cargar un archivo SVG que contenga contenido dañino como etiquetas \"(script)\".&#xa0;El enlace directo a ese archivo puede ser enviado a otros usuarios o visitantes al sitio.&#xa0;Si la víctima abre ese enlace en un navegador donde ha iniciado sesión en Kirby, el script se ejecutará y puede, por ejemplo, desencadenar peticiones a la API de Kirby con los permisos de la víctima.&#xa0;Esta vulnerabilidad es crítica si puede tener atacantes potenciales en su grupo de usuarios autenticados del Panel, ya que pueden escalar sus privilegios si consiguen acceso a la sesión del Panel de un usuario administrador.&#xa0;Dependiendo de su sitio, son posibles otros ataques basados ??en JavaScript.&#xa0;Los visitantes sin acceso al Panel solo pueden usar este vector de ataque si su sitio permite la carga de archivos SVG en formularios de frontend y usted no&#xa0;sanea los archivos SVG cargados.&#xa0;El problema ha sido parcheado en Kirby versión 3.5.4.&#xa0;Actualice a esta o una versión posterior para corregir la vulnerabilidad.&#xa0;Los formularios de carga de frontend deben parchearse por separado dependiendo de cómo almacenan los archivos cargados.&#xa0;Si usa la función \"File::create()\", está protegido actualizando a 3.5.4+.&#xa0;Como solución alternativa, puede desencadenar la carga de archivos SVG en sus planos de archivo"
    }
  ],
  "lastModified": "2026-06-17T03:47:41.207",
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