In OpenStack Manila before 23.0.1, multiple Manila API operations on public shares do not verify that the caller owns the share. The API controllers authorize operations against the caller's own project context, then load a foreign public share without re-authorizing against the share's actual owner. This affects the following operations: allow_access: grant data-plane read/write access to another tenant's share; deny_access: revoke the owner's existing access rules; update_access: escalate access level (e.g., ro to rw); create_share_backup: exfiltrate share data via a backup created under the