medium5.3
CVE-2026-8204
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.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| composer | concrete5/concrete5 | < 9.5.1 | 9.5.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Concretecms | Concrete Cms | before 9.5.1 |