Keycloak DCR Validation Bypass Allows Token Forgery
CVE-2026-92857 Published on November 5, 2026
Keycloak-services: keycloak-services: dcr protocol mapper config not validated, allowing iat holders to forge sub and aud claims in signed tokens
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.
Vulnerability Analysis
CVE-2026-92857 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and no impact on availability.
Timeline
Reported to Red Hat.
Made public. 50 days later.
Weakness Type
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Products Associated with CVE-2026-92857
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