Leantime JSON-RPC API through version 3.9.0 contains a missing authorization vulnerability in the JSON-RPC dispatcher in app/Domain/Api/Controllers/Jsonrpc.php. The dispatcher does not enforce authorization before invoking service-layer methods, allowing an authenticated user to call methods or act on resources outside their intended permissions. For example, the editOwn method accepts a user-supplied user ID without verifying that it belongs to the caller, allowing an attacker to modify another user's account and set a new password, resulting in account takeover. This vulnerability is distinct from CVE-2026-59712 and CVE-2026-15509 because the root cause is the lack of centralized authorization enforcement in the JSON-RPC dispatcher rather than the behavior of an individual exposed method.