Concrete CMS up to 9.5.2 Express Entry Authorization privileges management

Summaryinfo

A vulnerability has been found in Concrete CMS up to 9.5.2 and classified as problematic. The affected element is an unknown function of the component Express Entry Authorization. Performing a manipulation results in privileges management. This vulnerability was named CVE-2026-81916. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Concrete CMS up to 9.5.2. This affects an unknown part of the component Express Entry Authorization. The manipulation with an unknown input leads to a privileges management vulnerability. CWE is classifying the issue as CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. This is going to have an impact on integrity. The summary by CVE is:

Concrete CMS before 9.5.3 evaluated the authorization check for an Express entry submission against the entity of the posted form rather than the entity identified by the dashboard route. As a result, a user permitted to add entries to one Express object could create entries in a different Express object outside their authorization scope, potentially polluting protected datasets, triggering workflows, or injecting content into administrative processes. The dashboard submit route resolved the mutated entity from the attacker-controlled route ID while the permission check validated the independently posted form's entity, and the submission proceeded because the two entities were never compared. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

The advisory is shared at documentation.concretecms.org. This vulnerability is uniquely identified as CVE-2026-81916 since 08/27/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are necessary for exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/11/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

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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