CVE-2026-2652: Authentication Bypass in mlflow/mlflow

Severity: high (CVSS 8.6 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 20.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-15 · updated 2026-06-17
Weakness: CWE-305

Description

A vulnerability in mlflow/mlflow versions 3.9.0 and earlier allows unauthenticated access to certain FastAPI routes when the server is started with authentication enabled (`--app-name basic-auth`) and served via uvicorn (ASGI). The FastAPI permission middleware only enforces authentication on `/gateway/` routes, leaving other routes such as the Job API (`/ajax-api/3.0/jobs/*`) and the OpenTelemetry trace ingestion API (`/v1/traces`) unprotected. This allows unauthenticated remote attackers to submit jobs, read job results, cancel running jobs, and inject arbitrary trace data into experiments. The issue arises from an architectural mismatch between Flask and FastAPI authentication mechanisms, where the `_find_fastapi_validator()` function fails to handle non-`/gateway/` paths, resulting in a complete authentication bypass. This vulnerability is fixed in version 3.10.0.

Affected products

mlflow/mlflow: before 3.10.0 — fixed in 3.10.0

How to fix

Upgrade to a fixed version: mlflow/mlflow 3.10.0. Check the vendor advisory for mitigations.

References

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