Vulnerability · Published Jun 3, 2026 · Assigned by @huntr_ai
CVE-2026-4035Environment Variable Resolution Vulnerability in mlflow/mlflow
High 7.7
In plain English
A high-severity security flaw in mlflow/mlflow from mlflow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A vulnerability in mlflow/mlflow versions prior to 3.11.0 allows for the resolution of environment variables in AI Gateway secrets, which can be exploited to exfiltrate sensitive server-side environment credentials to an attacker-controlled endpoint. This issue arises because the `api_key` field in gateway secrets can accept `$ENV_VAR` references, which are resolved against the MLflow server's environment during runtime. The resolved secrets are then sent in provider authentication headers to the configured upstream `api_base`. This vulnerability can be exploited by low-privileged authenticated users in basic-auth deployments or by unauthenticated users in default deployments without `basic-auth`. The impact includes potential leakage of sensitive credentials such as cloud artifact credentials (`AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`), which could lead to artifact poisoning and cross-boundary code execution in downstream environments. The issue is fixed in version 3.11.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | mlflow | 3.11.0 | GHSA-g35p-px32-whv6 |
| PyPI | mlflow | 3.11.0 | PYSEC-2026-2222 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| mlflow | mlflow/mlflow | unspecified – before 3.11.0 |
Weakness: CWE-201 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
References
- https://huntr.com/bounties/f8e591a0-0f19-4910-b82e-16c9956f2233
- https://github.com/mlflow/mlflow/commit/4a3f2f720cb4f058c9e0c5b883e0acc9ab64a7f3
- https://access.redhat.com/security/cve/CVE-2026-4035 vdb-entry, x_refsource_REDHAT
- RHBZ#2484318 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4035.json x_sadp-csaf-vex