Authentication Bypass in mlflow/mlflow Product by Databricks

CVE-2026-2652

What is CVE-2026-2652?

A vulnerability in mlflow/mlflow allows unauthenticated access to specific FastAPI routes, even when the server is configured to require authentication. The flaw occurs when the server runs with basic-auth, but the FastAPI permission middleware is only enforcing authentication on the /gateway/ routes. This oversight leaves critical endpoints, including the Job API and OpenTelemetry trace ingestion API, susceptible to exploitation. Unauthenticated attackers can submit jobs, retrieve job results, cancel ongoing jobs, and inject malicious trace data into experiments. This issue stems from an architectural inconsistency between Flask and FastAPI's authentication frameworks, particularly within the _find_fastapi_validator() function, which fails to manage non-gateway paths effectively. The vulnerability was addressed in version 3.10.0.

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