CVE-2026-8239: medium-severity vulnerability in Concrete CMS
Concrete CMS 9.5.0 and below is vulnerable to IDOR in '/ccm/frontend/conversations/get_rating'
Published · Updated
33Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 6.3epss 0.3%
from disclosure to weapon72 days
Published on NVDMay 21
1st PoC+72d
exploitation probability
0.3%top 76% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
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
Affected products
Concrete CMS · Concrete CMSpublic PoCs found — 1
githubgithub.com/aj2108/CVE-2026-8239★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — Concrete CMS
In the same product, most dangerous first.
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