{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-87028","assignerOrgId":"ff5b8ace-8b95-4078-9743-eac1ca5451de","state":"PUBLISHED","assignerShortName":"ConcreteCMS","dateReserved":"2026-09-08T18:06:45.237Z","datePublished":"2026-09-16T16:36:56.404Z","dateUpdated":"2026-09-17T17:34:03.193Z"},"containers":{"cna":{"providerMetadata":{"orgId":"ff5b8ace-8b95-4078-9743-eac1ca5451de","shortName":"ConcreteCMS","dateUpdated":"2026-09-16T16:36:56.404Z"},"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","problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-862","description":"CWE-862 Missing Authorization","type":"CWE"}]}],"impacts":[{"capecId":"CAPEC-1","descriptions":[{"lang":"en","value":"CAPEC-1 Accessing Functionality Not Properly Constrained by ACLs"}]}],"affected":[{"vendor":"Concrete CMS","product":"Concrete CMS","collectionURL":"https://github.com/concretecms/concretecms","repo":"https://github.com/concretecms/concretecms","versions":[{"status":"affected","version":"9.0.0","lessThanOrEqual":"9.5.3","versionType":"git"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"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.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p><span>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.&nbsp;</span>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.</p>"}]}],"references":[{"url":"https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes","tags":["release-notes"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":5.3,"vectorString":"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"}}],"credits":[{"lang":"en","value":"polio123","type":"finder"}],"source":{"defect":["HackerOne"],"advisory":"3995503","discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.5"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-17T17:33:44.182942Z","id":"CVE-2026-87028","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-17T17:34:03.193Z"}}]}}