Ghost CMS <=4.32 - Cross-Site Scripting

id: CVE-2021-29484

info:
  name: Ghost CMS <=4.32 - Cross-Site Scripting
  author: rootxharsh,iamnoooob
  severity: medium
  description: Ghost CMS 4.0.0 to 4.3.2 contains a DOM cross-site scripting vulnerability. An unused endpoint added during the development of 4.0.0 allows attackers to gain access by getting logged-in users to click a link containing malicious code.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary JavaScript code in the context of the victim's browser, leading to potential data theft, session hijacking, or defacement of the affected website.
  remediation: This issue has been fixed in 4.3.3.
  reference:
    - https://github.com/TryGhost/Ghost/security/advisories/GHSA-9fgx-q25h-jxrg
    - https://www.npmjs.com/package/ghost
    - https://forum.ghost.org/t/critical-security-update-available-for-ghost-4-x/22290
    - https://nvd.nist.gov/vuln/detail/CVE-2021-29484
    - https://github.com/ARPSyndicate/cvemon
    - https://github.com/TryGhost/Ghost/blob/95651b33a66f3240535a61999b292a725f1b3317/core/server/web/admin/views/preview.html
    - https://www.sonarsource.com/blog/ghost-admin-takeover/
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
    cvss-score: 6.8
    cve-id: CVE-2021-29484
    cwe-id: CWE-79
    epss-score: 0.07935
    epss-percentile: 0.94021
    cpe: cpe:2.3:a:ghost:ghost:*:*:*:*:*:node.js:*:*
  metadata:
    max-request: 1
    vendor: ghost
    product: ghost
    framework: node.js
    shodan-query: http.component:"ghost"
  tags: cve2021,cve,xss,ghost,node.js,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/ghost/preview"

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - 'XMLHttpRequest.prototype.open = XMLHttpRequest.prototype.send'
          - 'top.postMessage('
        condition: and

      - type: word
        part: header
        words:
          - 'text/html'

      - type: status
        status:
          - 200
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