Budibase is an open-source low-code platform. Prior to 3.39.24, POST /api/public/v1/roles/assign called validateGlobalRoleUpdate without checking appBuilder.appId or role.appId in packages/server/src/api/controllers/public/globalRoleValidation.ts. An app-scoped builder could scope the request to an app they control and then grant themselves builder access or an arbitrary role in another app, exposing that app data, datasource configuration, and automations. This issue is fixed in version 3.39.24.

Affected: npm: @budibase/server

### Summary

Budibase `3.39.19` (commit `03fbabae4`) is affected by a privilege-escalation / missing-authorization flaw in the public role-assignment API. An **app-scoped builder** (a user who builds only specific apps — `user.builder.apps = [appA]`, not a global builder or admin) can grant **themselves builder access to ANY other app in the tenant**, or assign themselves/any user an arbitrary data-plane role (e.g. `ADMIN`) in any app, by calling `POST /api/public/v1/roles/assign`. The endpoint only authorizes the two *global* flags (`admin`, `builder`); the per-app `appBuilder` and `role:{appId,roleId}` grant vectors are passed to the backend **without any authorization check that the caller controls the target app**. Reproduced in a local authorized lab using the verbatim authorization-gate and SDK logic.

This is an incomplete fix of the role-assignment hardening in commit `d63d1d9054` ("Inline public user global role validation"), which only ever validated the global flags.

### Details

The issue is caused by authorization being implemented as a **flag-level allowlist** (`admin`/`builder`) instead of validating the *scope* the caller is granting.

Relevant code paths:

- `packages/server/src/api/controllers/public/globalRoleValidation.ts` — `validateGlobalRoleUpdate(ctx, roleUpdate)` only checks `roleUpdate.admin` (requires `isAdmin`) and `roleUpdate.builder` (requires `isGlobalBuilder`). The `GlobalRoleUpdate` interface declares only `{ builder?, admin? }`; `appBuilder…