MLflow 3.17.1 and prior Path Traversal via Trace ID API

Summary

MLflow 3.17.1 and earlier contains a path traversal vulnerability in the FileStore tracking backend that allows unauthenticated attackers to control filesystem paths by submitting a crafted trace ID containing traversal sequences to the POST /api/3.0/mlflow/traces endpoint. Attackers can exploit FileStore.start_trace() to write trace_info.yaml, request_metadata, and tag files with attacker-controlled metadata outside the intended experiment trace directory, subject to the server process's filesystem permissions. FileStore is the default tracking backend before MLflow 3.7.0 and opt-in thereafter (the default changed to a SQLite database), so deployments in the earlier part of the affected range are vulnerable without special configuration while later ones are affected only when FileStore is explicitly selected.

Timeline

1. Oct 19, 2026, 9:05 PM UTCCVE published
2. Oct 19, 2026, 9:36 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: yes · Technical impact: partial

3. Oct 27, 2026, 10:14 AM UTCRecord last updated

Affected versions

• mlflow mlflow

  through 3.17.1

• mlflowPyPI

  fixed in 3.17.2

• mlflowBitnami

  through 3.17.2

References 3