CVE-2026-92857 Keycloak-services: keycloak-services: dcr protocol mapper config not validated, allowing iat holders to forge sub and aud claims in signed tokens

Description

Keycloak provides a Dynamic Client Registration feature that allows users with specific tokens to register their own applications. A flaw in how Keycloak validates these registration requests allows an attacker to create a malicious application that forges identity information. By mapping their own user profile details to protected fields like the user ID (sub) or intended audience (aud), an attacker can generate signed security tokens that make them appear to be a different user. This could allow an attacker to impersonate other users or gain unauthorized access to services that rely on these tokens for identity verification.

Exploitable remotely over the network, with an ordinary account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Affected products and versions