Concrete CMS 9 through 9.5.3 did not confirm that a board InstanceItem submitted to the custom-slot preview endpoint belonged to the board instance the requesting user was authorized to edit, and did not enforce page-view permission before generating page-backed summary content. As a result, an authenticated user holding edit-board-contents permission on a single board instance could submit the identifier of an item belonging to a different board instance and receive summary fields, including the page title and description, of an underlying page the same user was otherwise forbidden to view. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Pakung for reporting.

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00272.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Concrete CMS Concrete CMS unaffected
Version Status Constraints
9.0.0 affected ≤ 9.5.3

No data.

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes cve-icon cve-icon
History

Fri, 18 Sep 2026 03:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 16 Sep 2026 16:45:00 +0000

Type Values Removed Values Added
Description Concrete CMS 9 through 9.5.3 did not confirm that a board InstanceItem submitted to the custom-slot preview endpoint belonged to the board instance the requesting user was authorized to edit, and did not enforce page-view permission before generating page-backed summary content. As a result, an authenticated user holding edit-board-contents permission on a single board instance could submit the identifier of an item belonging to a different board instance and receive summary fields, including the page title and description, of an underlying page the same user was otherwise forbidden to view. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Pakung for reporting.
Title Cross-Board IDOR in the Board Custom Slot Preview in Concrete CMS 9.0.0 through 9.5.3 Discloses Restricted Page Summary Fields
Weaknesses CWE-862
References
Metrics cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: ConcreteCMS

Published:

Updated: 2026-09-17T17:34:03.193Z

Reserved: 2026-09-08T18:06:45.237Z

Link: CVE-2026-87028

cve-icon Vulnrichment

Updated: 2026-09-17T17:33:52.423Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-09-16T17:18:16.560

Modified: 2026-09-17T18:17:12.643

Link: CVE-2026-87028

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-18T02:15:17Z

Weaknesses