Which products and versions are affected by CVE-2026-6826?

Affected: Concrete CMS (Concretecms) versions >= 5.0; concrete5/concrete5 (composer). The full list is in the CVE brief.

Is CVE-2026-6826 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Is CVE-2026-6826 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2026-6826?

No public exploit code is known.

Is there a fix for CVE-2026-6826?

Fixed versions are available, including concrete5/concrete5 9.5.1, Concrete CMS 9.5.1.

How urgently should CVE-2026-6826 be patched?

Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.

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Vulnerability Intelligence

CVE-2026-6826

Medium

Concrete 9.5.0 and below has file usage disclosure via missing permission check in Usage controller

Published May 21, 2026 · Updated Sep 10, 2026 · Also known as GHSA-4g7q-44qp-cc5c

Key Facts

Routine patching

CVE-2026-6826 is a medium-severity vulnerability (CVSS 6.9 v4) affecting Concrete CMS (Concretecms), concrete5/concrete5 (composer).
It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
EPSS estimates a 1.3% probability of exploitation in the next 30 days.
Fixed versions are available, including concrete5/concrete5 9.5.1, Concrete CMS 9.5.1.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.

CVSS v4

6.9

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS (30-day exploit likelihood)

1.3%

Higher than 69.6% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

None known

Get the full CVE-2026-6826 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

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.

Affected Products

3 affected entries in total

Product	Affected versions	Fixed in
Concrete CMSConcretecms	>= 5.0	9.5.1
concrete5/concrete5composer	See advisory	9.5.1

Patched Releases

concrete5/concrete5

9.5.1

Concrete CMS

9.5.1

Timeline

Publicly disclosed
May 21, 2026
Last updated
Sep 10, 2026

Weakness Type

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

FAQ

Common Questions.

Concrete CMS 9.5.0 and below is vulnerable to unauthenticated file usage disclosure via missing permission check in the usage controller.
Affected: Concrete CMS (Concretecms) versions >= 5.0; concrete5/concrete5 (composer). The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including concrete5/concrete5 9.5.1, Concrete CMS 9.5.1.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.

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