CVE-2026-2652

Authentication Bypass in mlflow/mlflow

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

mlflow · mlflow/mlflow

CVSS v3.0 HUNTR

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

EPSS

1.41% chance of exploitation in the next 30 days, 72nd percentile

Nuclei

high · CWE-306

Published

2026-05-15

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-2652.yaml

Security advisories

• https://huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756
• advisories/GHSA-75cm-x2w3-8mgf
• mlflow/mlflow/commit/bb62e773263c14e9ba4d1a82fe72d0de2442c6aa

References

• CVE Record
• NVD entry