OIDC email_verified claim incorrectly applied to userinfo email

Summary

A flaw exists in the org.keycloak.broker.oidc package where the OIDC broker incorrectly synchronizes the email_verified claim. When an OIDC identity provider is configured with trustEmail=true and the userinfo endpoint is enabled, Keycloak retrieves the email address from the userinfo response but retrieves the email_verified status exclusively from the id_token. The root cause is a lack of validation ensuring that the email_verified claim in the id_token actually refers to the email address returned by the userinfo endpoint. If these two sources return different email addresses, the id_token's email_verified=true claim is blindly applied to the userinfo email. Exploitation Conditions: The OIDC identity provider must have trustEmail set to true (non-default). The attacker must control or have compromised the upstream OIDC provider. Concrete Impact: Mark arbitrary email addresses as verified in the Keycloak database. Bypass email-based security controls or verification workflows. Potential account takeover if the application relies solely on the email_verified flag from the IdP to link accounts. Successful exploitation allows an attacker to cause an arbitrary email address to be marked as verified in Keycloak without proper validation. Red Hat severity: Moderate — CVSS 4.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N). Weakness: CWE-1288.