Concrete CMS 8.3.0 through 9.5.2 is vulnerable to an authorization bypass through user-controlled key (cross-calendar IDOR) in the Calendar event edit dialog

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68527
StatePUBLISHED
AssignerConcreteCMS
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-10 19:17:32 UTC
Updated2026-09-10 19:58:20 UTC
DescriptionConcrete CMS versions 8.3.0 through 9.5.2 are vulnerable to an authorization bypass in the Calendar event edit dialog (concrete/controllers/dialog/event/edit.php). The dialog checked permissions against the calendar identifier supplied in the request rather than the calendar owning the targeted event occurrence. A user with the "Add Event" permission on a single calendar could read and overwrite events on calendars they were not permitted to access, and could delete an event's original local occurrence. Publishing the injected version to the live calendar, which demotes the previously approved version, additionally required the actor's approve_calendar_event workflow rights or an auto-approving workflow. The Concrete CMS Security Team gave this a rank of 5.9 with CVSS 4.0 vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Risk And Classification

Primary CVSS: v4.0 5.9 MEDIUM from ff5b8ace-8b95-4078-9743-eac1ca5451de

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/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

Problem Types: CWE-639 | CWE-639 CWE-639 Insecure Direct Object Reference (IDOR)

VersionSourceTypeScoreSeverityVector
4.0ff5b8ace-8b95-4078-9743-eac1ca5451deSecondary5.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
High
User Interaction
None
Confidentiality
Low
Integrity
High
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Concrete CMS Concrete CMS affected 8.3.0 9.5.2 git Not specified

References

ReferenceSourceLinkTags
documentation.concretecms.org/9-x/developers/introduction/version-history/953-release-notes ff5b8ace-8b95-4078-9743-eac1ca5451de documentation.concretecms.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: winstoncrooker (en)

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