[Bugfix][Frontend] Require API key for top-level control-plane endpoints

tests/entrypoints/serve/middleware/test_authentication_middleware.py

@@ -130,6 +130,38 @@ def test_auto_discovered_protected_routes_require_auth(task_routes):
         )
 
 
+CONTROL_PLANE_PATHS = (
+    "/abort_requests",
+    "/detokenize",
+    "/is_scaling_elastic_ep",
+    "/scale_elastic_ep",
+    "/start_profile",
+    "/stop_profile",
+    "/tokenize",
+)
+
+
+def test_control_plane_routes_require_auth():
+    """Stateful control-plane endpoints are mounted at the top level
+    (outside the /v1, /v2, /inference, /cohere prefixes) but must still
+    be authenticated when an API key is configured."""
+    mock_routes = [(path, ["POST"]) for path in CONTROL_PLANE_PATHS]
+    app = _create_app_with_mock_routes(mock_routes)
+    client = TestClient(app)
+
+    for path in CONTROL_PLANE_PATHS:
+        assert path.startswith(GUARDED_PREFIX), f"{path} must be guarded"
+
+        resp = client.post(path)
+        assert resp.status_code == 401, f"POST {path} should reject missing token"
+
+        resp = client.post(path, headers={"Authorization": "Bearer wrong"})
+        assert resp.status_code == 401, f"POST {path} should reject invalid token"
+
+        resp = client.post(path, headers={"Authorization": "Bearer valid-token"})
+        assert resp.status_code == 200, f"POST {path} should accept valid token"
+
+
 def test_auto_discovered_unprotected_routes_no_auth(task_routes):
     """For every auto-discovered route that does NOT start with a guarded
     prefix, verify that no authentication is required."""

vllm/entrypoints/serve/middleware/authenticate.py

@@ -8,7 +8,26 @@
 from starlette.responses import JSONResponse
 from starlette.types import ASGIApp, Receive, Scope, Send
 
-GUARDED_PREFIX = ("/v1", "/v2", "/inference", "/cohere")
+# Paths that require authentication when an API key is configured.
+# Besides the OpenAI-compatible API prefixes, this also covers stateful
+# control-plane endpoints that are mounted outside those prefixes
+# (/tokenize, /scale_elastic_ep, /abort_requests, /start_profile, ...).
+# They mutate or introspect engine state, so they must not be reachable
+# unauthenticated while the rest of the API is behind --api-key.
+# Note: "/tokenize" also covers the /tokenizer_info endpoint.
+GUARDED_PREFIX = (
+    "/v1",
+    "/v2",
+    "/inference",
+    "/cohere",
+    "/abort_requests",
+    "/detokenize",
+    "/is_scaling_elastic_ep",
+    "/scale_elastic_ep",
+    "/start_profile",
+    "/stop_profile",
+    "/tokenize",
+)
 
 
 class AuthenticationMiddleware: