SecuriTricks - 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.

Product(s) Impacted

Vendor	Product	Versions
Concretecms	Concrete Cms	9.5.0, *

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-639

Authorization Bypass Through User-Controlled Key

The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	concretecms	concrete_cms	9.5.0	/	/	/	/	/	/	/
a	concretecms	concrete_cms	/	/	/	/	/	/	/	/

References

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

CVSS Score

6.3 / 10

CVSS Data - 4.0

Attack Vector: NETWORK
Attack Complexity: LOW
Attack Requirements: PRESENT
Privileges Required: NONE
User Interaction: NONE
Scope:
Confidentiality Impact: LOW
Integrity Impact: NONE
Availability Impact: NONE
Exploit Maturity: NOT_DEFINED

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

View Vector String

Timeline

Published: May 21, 2026, 9:16 p.m.
Last Modified: May 21, 2026, 9:16 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

ff5b8ace-8b95-4078-9743-eac1ca5451de

CVE-2026-8204