Keycloak-services: keycloak-services: cross-session email verification proof not bound to upstream identity for social providers

A flaw was found in the first-broker-login flow of the Keycloak identity management service. When a user links a social identity provider account to their local account, the verification proof generated is not strictly bound to the specific upstream identity being verified. This allows an attacker with a different account on the same social provider to intercept the process and link their own account to the victim's local profile, gaining unauthorized access.