CVE-2026-8204
Concrete CMS 9.5.0 and below is vulnerable to Authorization Bypass in the Calendar Event Frontend Dialog
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
Concrete CMS 9.5.0 and below is vulnerable to authorization Bypass in the Calendar Event Frontend Dialog which can allow cross-calendar data disclosure. A public calendar block can be used as a pivot point to access private calendar data. 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 Winston Crooker for reporting.
| CWE | CWE-639 |
| Vendor | concrete cms |
| Product | concrete cms |
| Published | May 21, 2026 |
| Last Updated | May 22, 2026 |
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Affected Versions
Concrete CMS / Concrete CMS
5 ≤ 9.5.0
References
Credits
Winston Crooker