CVE 2026 18570

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.

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 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.

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 ).

The following CVSS metrics and score provided are preliminary and subject to review.

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

Technical Impact: Read Application Data; Read Files or Directories

An attacker could read sensitive data, either by reading the data directly from a data store that is not restricted, or by accessing insufficiently-protected, privileged functionality to read the data.

Technical Impact: Modify Application Data; Modify Files or Directories

An attacker could modify sensitive data, either by writing the data directly to a data store that is not restricted, or by accessing insufficiently-protected, privileged functionality to write the data.

Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism

An attacker could gain privileges by modifying or reading critical data directly, or by accessing privileged functionality.

Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)

An attacker could gain unauthorized access to resources on the system and excessively consume those resources, leading to a denial of service.

Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue.

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