MEDIUM5.3

GHSA-x2fp-hj8c-mmxh

Concrete CMS is vulnerable to authorization bypass in the Calendar Event Frontend Dialog

Quick fix

GHSA-x2fp-hj8c-mmxh — concrete5/concrete5: upgrade to the fixed version with the command below.

composer require concrete5/concrete5:^9.5.1

Details

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.

Are you affected?

Enter the version of the package you're using.

Affected packages

Packagist/concrete5/concrete5

Introduced in: 0Fixed in: 9.5.1

Fixcomposer require concrete5/concrete5:^9.5.1

References

https://nvd.nist.gov/vuln/detail/CVE-2026-8204[ADVISORY]
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes[WEB]
https://github.com/concretecms/concretecms[PACKAGE]