Medium (4.8) in redhat build of keycloak. EPSS 0.3% chance of exploitation in the next 30 days.
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 userinfo endpoint must be enabled (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.
Severity
CVSS 3.1
4.8 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS
0.3% chance of exploitation in the next 30 days; higher than 20% of CVEs (scores of 2026-10-31)