PT-2026-42560 · Concrete Cms · Concrete Cms

Tristan Madani · Published 2026-05-21 · Updated 2026-05-21 · CVE-2026-8238

Mitre

CVSS v4.0

6.3

Medium

Base vector

AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

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.

Fix

Missing Authorization

Weakness Enumeration

CWE-862

Related Identifiers

CVE-2026-8238

Affected Products

Concrete Cms

References · 2

• https://nvd.nist.gov/vuln/detail/CVE-2026-8238 · Security Note
• https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes · Note