DescriptionNetherman Portal del Hermano (portaldelhermano.es) before 2026-10-06 contains a broken authentication vulnerability in its password-recovery flow at the POST /password/create-access and POST /password/email endpoints, allowing unauthenticated attackers to take over any member account across all tenants by exploiting the lack of rate limiting and distinct error messages that act as oracles for each of the four identity-verification factors (DNI, date of birth, phone number, last four IBAN digits). Attackers can confirm the DNI via the oracle, brute-force the date of birth and IBAN digits, obtain the phone number through open-source intelligence, then submit an attacker-controlled email field so the password reset link is delivered to them, enabling full account takeover including profile data, full IBAN, and fiscal documents.