CVE-2026-6826: Concrete CMS is vulnerable to unauthenticated file usage disclosure

May 21, 2026 (updated June 23, 2026)

Concrete CMS 9.5.0 and below is vulnerable to unauthenticated file usage disclosure via missing permission check in the usage controller. 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. Concrete CMS thanks Eldudareeno for reporting this issue.

References

documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
github.com/advisories/GHSA-4g7q-44qp-cc5c
nvd.nist.gov/vuln/detail/CVE-2026-6826

Code Behaviors & Features

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