CVE-2026-18570
Description
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.
Statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires the attacker to have delegated client creation privileges and the realm must have a specific policy configuration. Successful exploitation allows an attacker to bypass client scope restrictions and obtain tokens with unauthorized permissions. The vulnerability's root cause is the failure of the policy executor to account for default server behavior when the fullScopeAllowed field is missing from a request.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.4 | N/A | 5.4 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Acknowledgements
Red Hat would like to thank Paul Bottinelli (Trail of Bits in collaboration with OpenAI) for reporting this issue.
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