RustFS: AddServiceAccount Handler Allows Creation of Root-Parent Service Accounts

RustFS is a distributed object storage system built in Rust. RustFS AddServiceAccount in rustfs/src/admin/handlers/service_account.rs accepts an attacker-controlled target_user after only checking CreateServiceAccountAdminAction, passes it to new_service_account, and prepare_service_account_auth sets is_owner for the resulting root-parent service account. This issue is fixed in version 1.0.0-beta.11.