A flaw was found in Keycloak. When an authenticated attacker attempts to merge accounts with another existing account during an identity provider (IdP) login, the attacker will subsequently be prompted to review profile information. This vulnerability allows the attacker to modify their email address to match that of a victims account, triggering a verification email sent to the victims email address. The attackers email address is not present in the verification email content, making it a potential phishing opportunity. If the victim clicks the verification link, the attacker can gain access to the victims account.
The product does not properly verify that the source of data or communication is valid.