CVE-2026-8239

Name: CVE-2026-8239
Creator: NVD / NIST
Published: 2026-05-21T22:16:50.01+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.3/10EPSS 0.19%

Last modified Jun 17, 2026

CVE-2026-8239 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. 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.4.0 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.. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

Description

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.4.0 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 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS 4.0

6.3/10

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.19%

9.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

Affected Software

Vendor	Product	Versions
Concretecms	Concrete Cms	< 9.5.1

References

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notesRelease Notes

Timeline

Published: May 21, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-8239?

How severe is CVE-2026-8239?

CVE-2026-8239 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.

How do I fix CVE-2026-8239?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-8239?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST