A flaw was found in the offlineaccess scope in Keycloak. This issue would affect users of shared computers more (especially if cookies are not cleared), due to a lack of root session validation, and the reuse of session ids across root and user authentication sessions. This enables an attacker to resolve a user session attached to a previously authenticated user; when utilizing the refresh token, they will be issued a token for the original user.

Keycloak's device authorization grant does not correctly validate the device code and client ID. An attacker client could abuse the missing validation to spoof a client consent request and trick an authed admin into granting consent to a malicious OAuth client, or possible unauthorized access to an existing OAuth client.

A flaw was found in Keycloak. A Keycloak server configured to support mTLS authentication for OAuth/OpenID clients does not properly verify the client certificate chain. A client that possesses a proper certificate can authorize itself as any other client, therefore, access data that belongs to other clients.