CVE-2026-81906 Details
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.
A vulnerability exists in Concrete CMS OAuth callback login path in versions prior to 9.5.3. The issue arises because the login process did not verify if an account was active or if the email had been validated before creating a session. As a result, a deactivated or unvalidated user with an existing OAuth binding could authenticate and receive a fully authenticated session for the callback response. This login would be recorded, and login events dispatched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 11, 2026CISA-ADP
Assessed Sep 11, 2026References 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 LinkRelease NotesVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-288 | Authentication Bypass Using an Alternate Path or Channel | ConcreteCMS |
Affected Products
| Product | Versions |
|---|---|
| Concrete CMS | < 9.5.3 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 11, 2026 | CVE Modified | CISA-ADP |
| Sep 11, 2026 | New CVE Received | ConcreteCMS |