Ech0 authenticated user-list exposed data via public `/api/allusers` endpoint

Summary

A public access-control flaw allows unauthenticated users to retrieve the full user list from GET /api/allusers. This exposes user profile metadata to anyone who can reach the application and enables remote user enumeration.

Details

The vulnerable route is registered as a public endpoint:

• internal/router/user.go:17
• appRouterGroup.PublicRouterGroup.GET("/allusers", h.UserHandler.GetAllUsers())

However, the handler appears to have been intended as an authenticated endpoint:

• internal/handler/user/user.go:177-185
• API annotations indicate an authentication requirement via @Security ApiKeyAuth

This creates a mismatch between the documented security model and the actual routing configuration. As a result, requests to GET /api/allusers succeed without authentication and return user records, including profile metadata such as usernames, email addresses, role-related flags, avatar values, and locale information.

A negative control against another endpoint that correctly requires authentication further supports that this exposure is unintended: GET /api/user returns 401 Unauthorized when no token is supplied, while GET /api/allusers remains publicly accessible.

Impact

• Type: Access control bypass / unauthenticated data exposure
• Who is impacted: Any deployment exposing the API to untrusted networks, and all users whose profile metadata is returned by the endpoint
• Security impact: Enables remote user enumeration and disclosure of user profile metadata, which may facilitate account reconnaissance, phishing, and targeted credential attacks
• Attack preconditions: None beyond network access to the affected API endpoint