CVE-2026-18570 in Build of Keycloak
Summary
by MITRE • 08/02/2026
A flaw was found in the full-scope-disabled client-policy executor within the keycloak-services component. This component is responsible for enforcing security policies during client registration and configuration in Red Hat Build of Keycloak. The issue occurs because the executor only validates the fullScopeAllowed field when it is explicitly provided in a request. By omitting this field, a delegated user can bypass the policy, resulting in a client created with full scope access. This allows the client to obtain tokens with unauthorized role mappings.
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Analysis
by VulDB Data Team • 08/02/2026
This vulnerability exists within the keycloak-services component of Red Hat Build of Keycloak, specifically affecting the full-scope-disabled client-policy executor that governs security policy enforcement during client registration and configuration processes. The flaw represents a critical authorization bypass issue that undermines the core security model of the identity management system. When a delegated user submits a client registration request without explicitly providing the fullScopeAllowed field, the executor fails to perform mandatory validation checks, creating an exploitable gap in the access control mechanism.
The technical implementation of this vulnerability stems from improper input validation within the policy enforcement logic. The executor is designed to validate the fullScopeAllowed field only when it appears in the request payload, but does not enforce default security policies when this field is omitted entirely. This design flaw allows malicious or unauthorized users to create clients that automatically inherit full scope access privileges without proper authorization. The vulnerability manifests because the system assumes that explicit field omission indicates intentional configuration rather than a security oversight.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables unauthorized role mappings and token generation with elevated permissions. An attacker who successfully exploits this flaw can create clients that bypass all scope restrictions, potentially gaining access to sensitive data, privileged operations, and unauthorized system resources. This represents a significant risk to organizations relying on Keycloak for identity management, as compromised delegated users can effectively circumvent the intended security boundaries.
The vulnerability aligns with CWE-693 Protection Mechanism Failure, specifically relating to inadequate validation of security-relevant parameters that should be enforced regardless of user input. From an ATT&CK perspective, this flaw maps to privilege escalation techniques and credential access patterns where adversaries establish persistent access through unauthorized client configurations. Organizations using Keycloak for authentication and authorization services face substantial risk from this vulnerability, as it directly compromises the integrity of their security policies and potentially exposes sensitive infrastructure components.
Mitigation strategies should focus on implementing mandatory validation checks for all security-relevant parameters, including default enforcement of scope restrictions when fields are omitted. System administrators should review existing client configurations to identify potential unauthorized full-scope clients and implement proper access controls for delegated user permissions. Additionally, organizations should consider updating to patched versions of Keycloak that enforce strict validation of the fullScopeAllowed field regardless of its presence in incoming requests, ensuring that all client registrations adhere to defined security policies without exception.