CVE-2026-109371 [HIGH] – ZITADEL 3.0.0 before 4.18.0 contains a missing authentication vulnerability in the hosted

ZITADEL 3.0.0 before 4.18.0 contains a missing authentication vulnerability in the hosted Login V1 UI, where the change-username handler acts on the account bound to a login flow before any factor is verified. Unauthenticated attackers can submit a victim’s login name and then post a new username to rename any active human user, including administrators, locking them out.