GHSA-gqvg-gmmx-x4hm: MLFLOW_ALLOW_PICKLE_DESERIALIZATION=False safety control bypassed by mlflow.statsmodels flavor — RCE via crafted model artifact

MLflow introduced MLFLOW_ALLOW_PICKLE_DESERIALIZATION as a security control to prevent unsafe pickle.load execution during model loading, in response to CVE-2024-37052 through CVE-2024-37060. When set to False, operators expect all pickle deserialization to be blocked. The most recent related fix (#21188) patched a bypass in the pyfunc flavor.

However, the mlflow.statsmodels flavor completely omits this guard. An attacker who places a crafted MLmodel artifact into any accessible artifact store can trigger arbitrary code execution on any process that calls mlflow.pyfunc.load_model() against the malicious model — even when MLFLOW_ALLOW_PICKLE_DESERIALIZATION=False.

This is a security control bypass. The operator believes pickle RCE is mitigated; the statsmodels flavor silently ignores the control.