CVE-2026-8238

Concrete CMS 9.5.0 and below is vulnerable to IDOR in '/ccm/frontend/conversations/message_page' allowing unauthenticated read of any conversation message

Assigner: ConcreteCMS
Reserved: 09.05.2026 Published: 21.05.2026 Updated: 22.05.2026

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.

Metrics

CVSS 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
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	Concrete CMS
Product	Concrete CMS
Versions	Default: unaffected affected from 5.0 to 9.5.0 (incl.)

Vendor

Concrete CMS

Product

Concrete CMS

Versions

Default: unaffected

affected from 5.0 to 9.5.0 (incl.)

Credits

Tristan Madani finder

References

Problem Types

CWE-862 CWE

Impacts

CAPEC-122 Privilege Abuse