CVE-2026-33866 Authorization Bypass in MLflow AJAX Endpoint
Attackers can bypass authorization checks to download unauthorized model artifacts from MLflow experiments via a vulnerable AJAX endpoint.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33866?
CVE-2026-33866 is a medium-severity missing authorization vulnerability in Lfprojects Mlflow, published on 7 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
MLflow is vulnerable to an authorization bypass affecting the AJAX endpoint used to download saved model artifacts. Due to missing access‑control validation, a user without permissions to a given experiment can directly query this endpoint and retrieve model artifacts they are not authorized to access.
This issue affects MLflow version through 3.10.1
Weakness: CWE-862
Which versions are affected by CVE-2026-33866?
4 open source packages ship an affected version, including mlflow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mlflow Bitnami | All versions | 3.11.1 |
mlflow PyPI | All versions | 3.11.0rc0 |
mlflow PyPI | All versions | 3.11.0rc0 |
mlflow PyPI | All versions | 3.11.0rc0 |
Products include Lfprojects Mlflow.
How do I fix CVE-2026-33866?
Upgrade mlflow to a fixed version for your release line: 3.11.1 or 3.11.0rc0.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-33866 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33866 exists.
Other vulnerabilities in Lfprojects Mlflow
- CVE-2026-64849 MLflow Server-Side Request Forgery
- CVE-2025-15379 Command Injection in mlflow/mlflow
- CVE-2024-0520 Remote Code Execution due to Full Controlled File Write in mlflow/mlflow
- CVE-2023-6977 Path Traversal: '\..\filename'
- CVE-2023-6709 Improper Neutralization of Special Elements Used in a Template Engine in mlflow/mlflow
Sources
Also known as BIT-mlflow-2026-33866, GHSA-46r5-x6jq-v8g6, PYSEC-2026-94.