{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-81921", "assignerOrgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "state": "PUBLISHED", "assignerShortName": "ConcreteCMS", "dateReserved": "2026-08-27T18:23:01.366Z", "datePublished": "2026-09-15T18:48:52.840Z", "dateUpdated": "2026-09-15T19:28:31.335Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "shortName": "ConcreteCMS", "dateUpdated": "2026-09-15T18:48:52.840Z"}, "title": "In Concrete CMS 8.5.3 to 9,5,2, OAuth 2.0 Refresh-Token Grant Bypasses Account Status", "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": "8.5.3", "lessThanOrEqual": "9.5.2", "versionType": "git"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "Concrete CMS 8.5.3 through 9.5.2 enabled the OAuth 2.0 refresh-token grant using the unmodified upstream League grant, which issued new access tokens from a valid refresh token without re-checking the associated account's active status. A user who obtained a refresh token while active could therefore continue to mint valid access tokens after being deactivated or suspended (uIsActive=0), so deactivating an account did not revoke its API access.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L. Thanks sh4d0byss for reporting.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p><span>Concrete CMS 8.5.3 through 9.5.2 enabled the OAuth 2.0 refresh-token grant using the unmodified upstream League grant, which issued new access tokens from a valid refresh token without re-checking the associated account's active status. A user who obtained a refresh token while active could therefore continue to mint valid access tokens after being deactivated or suspended (uIsActive=0), so deactivating an account did not revoke its API access.&nbsp;</span>The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L. Thanks sh4d0byss for reporting.</p>"}]}], "references": [{"url": "https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes", "tags": ["release-notes"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "subConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "subIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "subAvailabilityImpact": "LOW", "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": "LOW", "baseScore": 2.3, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L"}}], "credits": [{"lang": "en", "value": "sh4d0byss", "type": "finder"}], "source": {"defect": ["HackerOne"], "advisory": "3873364", "discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.5"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-09-15T19:28:23.386520Z", "id": "CVE-2026-81921", "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": "2026-09-15T19:28:31.335Z"}}]}}

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