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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-05-21

Last Modified

2026-05-26

Generated

2026-07-02

AI Q&A

2026-05-22

EPSS Evaluated

2026-06-30

NVD

CVE-2026-8238

EUVD

EUVD-2026-31354

Affected Vendors & Products

Vendor	Product	Version / Range
concretecms	concrete_cms	to 9.5.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

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.

Attack-Flow Graph

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.

Hi! I’m here to help you understand CVE-2026-8238. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70