Information disclosure in Concrete Cms

CVE-2026-6826

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.

Vulnerability class: Information Disclosure

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.013 (68.9th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 68.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-6826: held from 0.015 to 0.013.

EPSS over last 30 days · oldest: 0.015 · newest: 0.013 · change: -0.002

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-6826?
CVE-2026-6826 is a medium-severity vulnerability in Concrete Cms, classified under Information Disclosure. CVSS score: 5.3/10. Published 2026-05-21.
How severe is CVE-2026-6826?
Medium severity. CVSS v3 base score is 5.3 out of 10.
Is CVE-2026-6826 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.