diff --git a/people-and-planet-ai/geospatial-classification/README.md b/people-and-planet-ai/geospatial-classification/README.md
index d366f6bbb18..c7f7793727c 100644
--- a/people-and-planet-ai/geospatial-classification/README.md
+++ b/people-and-planet-ai/geospatial-classification/README.md
@@ -11,6 +11,10 @@ This model uses satellite data to predict if a coal plant is turned on and produ
 * **Training the model**: [TensorFlow] in [Vertex AI]
 * **Getting predictions**: [TensorFlow] in [Cloud Run]
 
+## Serving app security configuration
+
+Set the `MODEL_DIR` environment variable to a trusted model artifact location before starting `serving_app`. The prediction endpoint no longer accepts a user-controlled bucket for model loading because loading untrusted TensorFlow/Keras artifacts can execute attacker-controlled code during deserialization.
+
 [Cloud Run]: https://cloud.google.com/run
 [Sentinel-2]: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2
 [Earth Engine]: https://earthengine.google.com/
diff --git a/people-and-planet-ai/geospatial-classification/serving_app/main.py b/people-and-planet-ai/geospatial-classification/serving_app/main.py
index 61c72509e10..f90275ff7ad 100644
--- a/people-and-planet-ai/geospatial-classification/serving_app/main.py
+++ b/people-and-planet-ai/geospatial-classification/serving_app/main.py
@@ -14,6 +14,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import os
+
 import flask
 
 app = flask.Flask(__name__)
@@ -28,15 +31,21 @@ def run_root() -> str:
     }
 
 
+def get_trusted_model_dir() -> str:
+    model_dir = os.environ.get("MODEL_DIR")
+    if not model_dir:
+        raise RuntimeError("MODEL_DIR must be set to a trusted model location.")
+    return model_dir
+
+
 @app.route("/predict", methods=["POST"])
 def run_predict() -> dict:
     import predict
 
     try:
         args = flask.request.get_json() or {}
-        bucket = args["bucket"]
-        model_dir = f"gs://{bucket}/model_output"
         data = args["data"]
+        model_dir = get_trusted_model_dir()
         predictions = predict.run(data, model_dir)
 
         return {
@@ -45,10 +54,9 @@ def run_predict() -> dict:
             "predictions": predictions,
         }
     except Exception as e:
-        return {"error": f"{type(e).__name__}: {e}"}
+        logging.exception(e)
+        return ({"error": f"{type(e).__name__}: {e}"}, 500)
 
 
 if __name__ == "__main__":
-    import os
-
     app.run(debug=True, host="0.0.0.0", port=int(os.environ.get("PORT", 8080)))
diff --git a/people-and-planet-ai/geospatial-classification/serving_app/requirements-test.txt b/people-and-planet-ai/geospatial-classification/serving_app/requirements-test.txt
new file mode 100644
index 00000000000..15d066af319
--- /dev/null
+++ b/people-and-planet-ai/geospatial-classification/serving_app/requirements-test.txt
@@ -0,0 +1 @@
+pytest==8.2.0
diff --git a/people-and-planet-ai/geospatial-classification/serving_app/test_main.py b/people-and-planet-ai/geospatial-classification/serving_app/test_main.py
new file mode 100644
index 00000000000..ec26d25a8dc
--- /dev/null
+++ b/people-and-planet-ai/geospatial-classification/serving_app/test_main.py
@@ -0,0 +1,101 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from collections.abc import Generator
+import sys
+import types
+
+from flask.testing import FlaskClient
+import pytest
+
+import main
+
+
+@pytest.fixture
+def client() -> Generator[FlaskClient, None, None]:
+    main.app.config.update(TESTING=True)
+    with main.app.test_client() as test_client:
+        yield test_client
+
+
+def test_predict_uses_trusted_model_dir_from_environment(
+    client: FlaskClient, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    calls: list[tuple[dict, str]] = []
+
+    def fake_run(data: dict, model_dir: str) -> dict:
+        calls.append((data, model_dir))
+        return {"predictions": [[0.42]]}
+
+    monkeypatch.setenv("MODEL_DIR", "gs://trusted-bucket/model_output")
+    monkeypatch.setitem(sys.modules, "predict", types.SimpleNamespace(run=fake_run))
+
+    response = client.post(
+        "/predict",
+        json={
+            "bucket": "attacker-bucket/evil-prefix",
+            "data": {
+                "band_1": [[1, 2, 3]],
+                "band_2": [[4, 5, 6]],
+                "band_3": [[7, 8, 9]],
+            },
+        },
+    )
+
+    assert response.status_code == 200
+    assert response.get_json() == {
+        "method": "predict",
+        "model_dir": "gs://trusted-bucket/model_output",
+        "predictions": {"predictions": [[0.42]]},
+    }
+    assert calls == [
+        (
+            {
+                "band_1": [[1, 2, 3]],
+                "band_2": [[4, 5, 6]],
+                "band_3": [[7, 8, 9]],
+            },
+            "gs://trusted-bucket/model_output",
+        )
+    ]
+
+
+def test_predict_returns_error_when_trusted_model_dir_is_missing(
+    client: FlaskClient, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.delenv("MODEL_DIR", raising=False)
+    monkeypatch.setitem(
+        sys.modules,
+        "predict",
+        types.SimpleNamespace(run=lambda data, model_dir: {"predictions": [[0.42]]}),
+    )
+
+    response = client.post(
+        "/predict",
+        json={
+            "bucket": "attacker-bucket/evil-prefix",
+            "data": {
+                "band_1": [[1, 2, 3]],
+                "band_2": [[4, 5, 6]],
+                "band_3": [[7, 8, 9]],
+            },
+        },
+    )
+
+    assert response.status_code == 500
+    assert response.get_json() == {
+        "error": "RuntimeError: MODEL_DIR must be set to a trusted model location."
+    }