CVE-2026-87028

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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes	Broken Link

Configurations

Configuration 1 (hide)

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*

History

21 Sep 2026, 17:51

Type	Values Removed	Values Added
References	~~() https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes -~~	() https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes - Broken Link
CPE		cpe:2.3:a:concretecms:concrete_cms::::::::
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 6.5
First Time		Concretecms Concretecms concrete Cms

16 Sep 2026, 17:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-16 17:18

Updated : 2026-09-21 17:51

NVD link : CVE-2026-87028

Mitre link : CVE-2026-87028

CVE.ORG link : CVE-2026-87028

JSON object : View

Products Affected

concretecms

concrete_cms

CWE

CWE-862

Missing Authorization

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