Concrete CMS up to 9.5.2 Express REST API includes improper authorization

Summaryinfo

A vulnerability categorized as problematic has been discovered in Concrete CMS up to 9.5.2. Affected by this issue is some unknown functionality of the component Express REST API. The manipulation of the argument includes results in improper authorization. This vulnerability is known as CVE-2026-18122. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as problematic has been found in Concrete CMS up to 9.5.2. Affected is an unknown functionality of the component Express REST API. The manipulation of the argument includes with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality. CVE summarizes:

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.

The advisory is shared for download at documentation.concretecms.org. This vulnerability is traded as CVE-2026-18122 since 07/28/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/11/2026). The MITRE ATT&CK project declares the attack technique as T1548.002.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Content Management System

Name

• Concrete CMS

Version

• 9.5.0
• 9.5.1
• 9.5.2

License

• open-source

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