Concrete CMS 9.5.0 and below is vulnerable to IDOR combined with a missing authentication gate for endpoint /ccm/system/dialogs/file/usage/{fID}

published 2026-05-21 5 mo ago modified 2026-09-10 1 mo ago also GHSA-58c8-vvqw-cm7m , EUVD-2026-31347

cvss: 4.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits: 0; none known, plus a Nuclei check

Concrete CMS 9.5.0 and below is vulnerable to IDOR combined with a missing authentication gate. The endpoint /ccm/system/dialogs/file/usage/{fID} accepts an integer file ID in the URL and returns internal site structure data (page IDs, versions, URL paths) to anyone who sends a GET request. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Patch / fix

fixed in 2

packagist concrete5/concrete5 9.5.1
concretecms concrete_cms 9.5.1

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 5 mo ago (2026-05-22)

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

Nuclei template Concrete CMS <9.5.1 - Unauthenticated File-Usage Internal Metadata Disclosure nuclei detection template

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/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
NVD	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	concrete5/concrete5	<9.5.1	9.5.1

Affected products

Concrete CMS Concrete CMS

Classification

Weakness

CWE-862 Missing Authorization

References

documentation.concretecms.org /9-x/developers/introduction/version-history/951-release-notes
release-notes, web
nvd.nist.gov /vuln/detail/CVE-2026-8236
advisory
github.com /concretecms/concretecms
package

Sources

CVE List CVE-2026-8236
GitHub Advisory GHSA-58c8-vvqw-cm7m
NVD CVE-2026-8236

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary