CVE-2026-8238

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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes	Release Notes

Configurations

Configuration 1 (hide)

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*

History

26 May 2026, 17:29

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 5.3
References	~~() https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes -~~	() https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes - Release Notes
First Time		Concretecms concrete Cms Concretecms
CPE		cpe:2.3:a:concretecms:concrete_cms::::::::

21 May 2026, 22:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-05-21 22:16

Updated : 2026-05-26 17:29

NVD link : CVE-2026-8238

Mitre link : CVE-2026-8238

CVE.ORG link : CVE-2026-8238

JSON object : View

Products Affected

concretecms

concrete_cms

CWE

CWE-862

Missing Authorization

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