CVE-2026-87028Medium· 6.5▾ SunlitConcrete 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 befo…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 35.8 · likelihood 0.1 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 19.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.3%
Last analysed / modified upstream
5.3 → 6.5
0.3% → 0.4%
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.
concrete_cms >= 9.0.0, < 9.5.3Upgrade past the affected range:
concrete_cms 9.5.3Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-87031Low· 2.7n Concrete CMS 9.2.0 through 9.5.3, the REST API user creation endpoint (POST /ccm/api/1.0/users, the add() method of concrete/src/Api/Controller/Users.php) did not perform a permission check before creating an account
CVE-2026-85387High· 7.1Concrete CMS before 9.5.4 re-authorized OAuth REST API requests from the bearer token alone and did not re-check the state of the account the token had been issued to
CVE-2026-18120Medium· 5.9Concrete CMS before 9.5.3 exposed a legacy Express entry search endpoint that returned entry result JSON without invoking the canViewExpressEntries() permission check applied by the normal dashboard and CSV Export flow
CVE-2026-85385Critical· 9.6Concrete CMS below 9.5.4 did not validate the user timezone value (uTimezone) on write and rendered it without output encoding on the Dashboard user management page, where Date::getTimezoneDisplayName() returns any non-IANA value unchang…
CVE-2026-85386Medium· 6.1Concrete CMS before 9.5.4 did not sanitize XML and XSLT documents uploaded through a public Form Block file-upload question
CVE-2026-18426Medium· 6.5Concrete CMS 9.0.0 through 9.5.2 did not enforce a block-level edit-permission check on the Express Form block's control-management actions, which relied solely on CSRF token validation