In short
- CVE-2026-8204 is a MEDIUM (CVSS 5.3) vulnerability affecting concrete5/concrete5, concrete cms (concretecms).
- Chance of exploitation in the next 30 days (EPSS): 0.21%, higher than 11.4% of all vulnerabilities.
- Fix: update to 9.5.1 or later.
Description
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.
NVD description
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.
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