Medium severity · published May 21, 2026
CVE-2026-6826
Concrete 9.5.0 and below has file usage disclosure via missing permission check in Usage controller
5.3
CVSS
1.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.5% · higher than 73% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CC
Concrete CMS · Concrete CMS
5.0 through 9.5.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-6826
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-6826
Release Notes
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
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