CVE-2026-8238
Analyzed Analyzed - Analysis Complete
IDOR Vulnerability in Concrete CMS Exposes Conversation Messages

Publication date: 2026-05-21

Last updated on: 2026-05-26

Assigner: ConcreteCMS

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.
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Meta Information
Published
2026-05-21
Last Modified
2026-05-26
Generated
2026-06-11
AI Q&A
2026-05-22
EPSS Evaluated
2026-06-10
NVD
CVE-2026-8238
EUVD
EUVD-2026-31354
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
concretecms concrete_cms to 9.5.1 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
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Executive Summary

This vulnerability is an Insecure Direct Object Reference (IDOR) in Concrete CMS version 9.5.0 and below. It occurs at the '/ccm/frontend/conversations/message_page' endpoint, which returns the full content of any conversation message.

An unauthenticated attacker can exploit this flaw to enumerate all conversation messages, including those from restricted pages, member-only areas, and the moderation queue. Additionally, file attachments with download URLs are exposed to the attacker.

Impact Analysis

This vulnerability can lead to unauthorized disclosure of sensitive information. Since an unauthenticated attacker can access conversation messages from restricted and member-only areas, confidential communications and file attachments may be exposed.

This exposure could result in privacy breaches, leakage of sensitive data, and potential misuse of the information obtained from these messages and attachments.

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