CVE-2026-8237

Concrete CMS 9.5.0 and below is vulnerable to IDOR. The `/ccm/frontend/conversations/message_detail` 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 Eldudareeno for reporting.

Affected products

Concrete Cms

Concretecms Concrete Cms

< 9.5.1

Fix

Available

CVSS 4.0

6.3 MEDIUM

CVSS 3.1

5.3 MEDIUM

EPSS

0.6% (48th percentile)

Weakness

CWE-862

NVD status

Analyzed

Published

2026-05-21

Attack patterns

CAPEC-122