CVE-2026-8239: Concrete CMS is vulnerable to IDOR

May 22, 2026 (updated June 24, 2026)

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.

References

documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
github.com/advisories/GHSA-2xp7-rpvc-pjwc
nvd.nist.gov/vuln/detail/CVE-2026-8239

Code Behaviors & Features

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