What is CVE-2026-8239?

CVE-2026-8239 is a medium-severity vulnerability in Concrete Cms, classified under Missing Authorization. CVSS score: 5.3/10. Published 2026-05-21.

How severe is CVE-2026-8239?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Auth bypass in Concrete Cms

CVE-2026-8239

Concrete CMS 9.5.0 and below is vulnerable to IDOR. The '/ccm/frontend/conversations/get_rating' endpoint confirms existence and returns rating score for any message by ID. The Concrete CMS security team gave this vulnerability a CVSS v.4…

Vulnerability class: Broken Access Control

EPSS: 0.000 (9.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Affected products

Concrete Cms — versions 5.0
Concretecms Concrete_cms

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

ff5b8ace-8b95-4078-9743-eac1ca5451de (release-notes, Release Notes)

Frequently asked questions

What is CVE-2026-8239?: CVE-2026-8239 is a medium-severity vulnerability in Concrete Cms, classified under Missing Authorization. CVSS score: 5.3/10. Published 2026-05-21.
How severe is CVE-2026-8239?: Medium severity. CVSS v3 base score is 5.3 out of 10.