CVE-2026-14781
Summary
by MITRE • 07/05/2026
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.
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Analysis
by VulDB Data Team • 07/05/2026
This vulnerability resides within the org.keycloak.broker.oidc package of the Keycloak identity management platform, representing a critical inconsistency in how email verification status is handled during OpenID Connect federated authentication processes. The flaw manifests when an OIDC identity provider is configured with trustEmail=true and the userinfo endpoint is enabled, creating a scenario where Keycloak's synchronization logic fails to properly validate the relationship between email addresses retrieved from different sources within the authentication flow.
The technical implementation defect stems from a fundamental lack of cross-validation between the email address obtained from the userinfo endpoint and the email_verified claim present in the id_token response. According to CWE-284 access control vulnerabilities, this represents a weakness in privilege management where the system incorrectly applies verification status across different email contexts without proper correlation checks. The vulnerability operates under the principle that when trustEmail is enabled, Keycloak assumes the email_verified flag from the id_token directly maps to the email address returned by userinfo, creating an implicit trust relationship that may not exist.
The operational impact of this vulnerability extends beyond simple data inconsistency, potentially enabling attackers to manipulate email verification states within the Keycloak database. This represents a significant security risk as it allows malicious actors to arbitrarily mark any email address as verified, effectively bypassing email-based security controls and verification workflows that organizations rely upon for account protection. The vulnerability is particularly dangerous in environments where applications depend on the email_verified flag from the identity provider as a primary mechanism for account linking or authentication validation.
From an ATT&CK framework perspective, this vulnerability maps to technique T1566.002 (Phishing: Spearphishing Attachment) and T1078.004 (Valid Accounts: Cloud Accounts) where attackers can exploit the verification bypass to gain unauthorized access to accounts or manipulate user permissions. The exploitation requires an attacker to control or compromise the upstream OIDC provider, making this a supply chain security concern that affects organizations relying on third-party identity providers.
The mitigation strategy requires implementing proper validation logic that ensures the email_verified claim in the id_token corresponds to the actual email address returned by the userinfo endpoint before applying verification status. Organizations should disable trustEmail functionality when not explicitly required, implement additional validation layers for federated identity claims, and consider monitoring for unexpected email verification status changes within their Keycloak instances. Security controls should also include regular audits of email verification states and implementation of multi-factor authentication mechanisms to reduce the impact of potential exploitation.
This vulnerability demonstrates the complexity of identity federation security where trust relationships between systems can be exploited when proper validation boundaries are not maintained, highlighting the need for comprehensive security testing of identity provider integration points and adherence to security standards such as those defined in NIST SP 800-63B for digital identity management.