What is GHSA-x2fp-hj8c-mmxh?

GHSA-x2fp-hj8c-mmxh is a security advisory published by GitHub Security Advisories with Medium severity. Concrete CMS 9.5.0 and below is vulnerable to authorization Bypass in the Calendar Event Frontend...

Which CVE IDs does GHSA-x2fp-hj8c-mmxh cover?

GHSA-x2fp-hj8c-mmxh covers the following CVE IDs: CVE-2026-8204. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

GHSA-x2fp-hj8c-mmxhMedium

Concrete CMS 9.5.0 and below is vulnerable to authorization Bypass in the Calendar Event Frontend...

Vendor

GitHub Security Advisories

Published

May 21, 2026

Last Modified

May 21, 2026

🔗 CVE IDs covered (1)

CVE-2026-8204 →

📋 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.

🔗 References (3)

https://nvd.nist.gov/vuln/detail/CVE-2026-8204
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
https://github.com/advisories/GHSA-x2fp-hj8c-mmxh