CVE-2026-6826: Concretecms Concrete CMS

Medium severity, CVSS 5.3. EPSS: 1.3% chance of exploitation in the next 30 days.

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.The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.9 with vector 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. Thanks Eldudareeno for reporting.

Affected products

• Concretecms Concrete CMS: before 9.5.1 (fixed in 9.5.1)

Published 2026-05-21. Last modified 2026-07-23.