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...

CVE-2026-87028

CVE-2026-87028 is a cross-board Insecure Direct Object Reference (IDOR) in the Board Custom Slot Preview endpoint of Concrete CMS 9.0.0 through 9.5.3 . The endpoint failed to verify that a submitted InstanceItem belonged to the board instance the requesting user was authorized to edit, and did no...