Not a U.S. government website. NDD is an independent vulnerability database by Volerion and is not affiliated with or endorsed by NIST or NVD.

CVE-2026-81921 Details

Description

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. 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.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:5.4 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.

URL	Source(s)	Tag(s)
https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes	ConcreteCMS	Broken Link

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-862	Missing Authorization	ConcreteCMS

Affected Products

Product	Versions
concretecms concrete cms	>= 8.5.3, < 9.5.3
CPE cpe:2.3:a:concretecms:concrete_cms:::::::: Remediation No remediation found in references.

Change History

3 change records found show changes

Date	Action	Recorded By
Sep 18, 2026	Initial Analysis	[email protected]
Sep 15, 2026	CVE Modified	CISA-ADP
Sep 15, 2026	New CVE Received	ConcreteCMS