CVE-2026-81906
[UNREVIEWED] OAuth Callback Login Bypasses Deactivated-Account Checks
- State
- Published
- Severity
- 6.3 Medium
- Published
- Sep 10, 2026
- Updated
- Sep 11, 2026
- Reserved
- Aug 27, 2026
Description
Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully authenticated for the callback response, with the login recorded and login events dispatched. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.3 Medium | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | ConcreteCMS |
Weaknesses
- CWE-288 Authentication bypass using an alternate path or channel
Affected Products
| Product | Versions |
|---|---|
Concrete CMSConcrete CMS |
|
References
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