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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.

PUBLISHED Reserved 2026-02-18 | Published 2026-05-15 | Updated 2026-05-15 | Assigner @huntr_ai




HIGH: 8.6CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L

Problem types

CWE-305 Authentication Bypass by Primary Weakness

Product status

Any version before 3.10.0
affected

References

huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756 exploit

huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756

github.com/...ommit/bb62e773263c14e9ba4d1a82fe72d0de2442c6aa

cve.org (CVE-2026-2652)

nvd.nist.gov (CVE-2026-2652)

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