Description
Concrete CMS 9.5.0 and below is vulnerable to IDOR. The '/ccm/frontend/conversations/message_page' endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. 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 Tristan Madani for reporting.
Published: 2026-05-21
Score: 6.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-qv3x-mffx-9gw8 Concrete CMS is vulnerable to IDOR
History

Tue, 26 May 2026 17:30:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}


Fri, 22 May 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 21 May 2026 22:45:00 +0000

Type Values Removed Values Added
First Time appeared Concretecms
Concretecms concrete Cms
Vendors & Products Concretecms
Concretecms concrete Cms

Thu, 21 May 2026 21:45:00 +0000

Type Values Removed Values Added
Description Concrete CMS 9.5.0 and below is vulnerable to IDOR. The '/ccm/frontend/conversations/message_page' endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. 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 Tristan Madani for reporting.
Title Concrete CMS 9.5.0 and below is vulnerable to IDOR in '/ccm/frontend/conversations/message_page' allowing unauthenticated read of any conversation message
Weaknesses CWE-862
References
Metrics cvssV4_0

{'score': 6.3, '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'}


Subscriptions

Concretecms Concrete Cms
cve-icon MITRE

Status: PUBLISHED

Assigner: ConcreteCMS

Published:

Updated: 2026-05-22T12:30:59.976Z

Reserved: 2026-05-09T15:48:41.906Z

Link: CVE-2026-8238

cve-icon Vulnrichment

Updated: 2026-05-22T12:30:56.075Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-21T22:16:49.893

Modified: 2026-06-17T11:03:42.167

Link: CVE-2026-8238

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-21T22:30:20Z

Weaknesses