Path Traversal Vulnerability in MLflow Affects FileStore Backend

CVE-2026-127202

What is CVE-2026-127202?

The MLflow FileStore backend prior to version 3.18.0 is vulnerable to a path traversal issue. An attacker can exploit this by submitting a malicious model_id parameter to the log outputs API, which may contain '../' sequences. This manipulation permits unauthenticated remote users to write data to arbitrary locations on the server’s filesystem by utilizing the POST /api/3.0/mlflow/runs/outputs endpoint. The consequences can be severe, enabling attackers to create directories and place files, such as a meta.yaml, at locations dictated by the server's configuration. This vulnerability primarily affects deployments where the FileStore backend is enabled, which was the default setting before version 3.7.0.

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