A malicious user could use this issue to access internal HTTP(s) servers and in the worst case (ie: aws instance) it could be abuse to get a remote code execution on the victim machine.
https://huntr.com/bounties/438b0524-da0e-4d08-976a-6f270c688393
https://github.com/mlflow/mlflow/commit/8174250f83352a04c2d42079f414759060458555