CVE-2026-18122
Deferred Deferred - Pending Action

Concrete CMS REST API Missing Authorization Exposure

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: ConcreteCMS

Description
Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entries via Missing Authorization; the Concrete CMS REST API's Express entry collection endpoint disabled the per-entry view permission check. An OAuth token with read scope for an Express entity could enumerate entries that its user context lacked permission to view, disclosing each entry's public identifier, URL, label, dates, and any attribute or associated-entry data requested via the includes parameter. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-11
AI Q&A
2026-09-11
EPSS Evaluated
N/A
NVD
CVE-2026-18122
EUVD
EUVD-2026-76161

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
concrete_cms concrete_cms From 9.2.0 (inc) to 9.5.2 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

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Executive Summary

Concrete CMS versions 9.2.0 to 9.5.2 have a vulnerability in the Express REST API list endpoint where authorization checks are missing. This allows an attacker with an OAuth token to read Express entries they are not permitted to view, exposing data like public identifiers, URLs, labels, dates, and attribute information.

Detection Guidance

To detect this vulnerability, check if your Concrete CMS REST API endpoints are exposing Express entry data without proper authorization. Review API logs for unauthorized access attempts or unusual enumeration of entries. Verify if the Express entry collection endpoint lacks permission checks for view access.

Impact Analysis

An attacker could exploit this to access sensitive data stored in Express entries, such as user information or other restricted content, even if they lack proper permissions. This could lead to data leaks or unauthorized access to confidential information.

Compliance Impact

This vulnerability could violate compliance requirements like GDPR or HIPAA by exposing personal or sensitive data to unauthorized users. Organizations using affected Concrete CMS versions may face legal and regulatory penalties due to unauthorized data access.

Mitigation Strategies

Immediately update Concrete CMS to a version beyond 9.5.2 to patch the missing authorization flaw. Review and restrict OAuth token scopes to the minimum required permissions. Audit API access logs for suspicious activity and ensure Express entry permissions are correctly enforced.

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