Keycloak on Red Hat Admin REST API GroupResource.addChild authorization

Summaryinfo

A vulnerability was found in Keycloak on Red Hat. It has been rated as problematic. This affects the function GroupResource.addChild of the component Admin REST API. Performing a manipulation results in authorization. This vulnerability is reported as CVE-2026-9099. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Keycloak on Red Hat (version unknown). It has been classified as problematic. This affects the function GroupResource.addChild of the component Admin REST API. The manipulation with an unknown input leads to a authorization vulnerability. CWE is classifying the issue as CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in Keycloak. A missing authorization check in the GroupResource.addChild() endpoint within the Admin REST API allows an authenticated user with limited administrative privileges to reparent any existing group. When Fine-Grained Admin Permissions v2 (FGAPv2) is enabled, an attacker with management rights over a single low-privilege group can reparent a highly privileged group (such as one possessing the realm-admin role) under their managed group. Because group permissions follow a hierarchical structure, this action unauthorizedly grants the attacker management and password-reset capabilities over the members of the targeted privileged group. An attacker can exploit this to reset an administrator's password, compromise the account, and achieve a full realm takeover, leading to a complete compromise of confidentiality, integrity, and availability.

It is possible to read the advisory at access.redhat.com. This vulnerability is uniquely identified as CVE-2026-9099 since 05/20/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. Additional levels of successful authentication are required for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/25/2026).

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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Name

• Keycloak

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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