CVE-2026-4035
Environment Variable Resolution Vulnerability in mlflow/mlflow
- State
- Published
- Severity
- 9.1 Critical
- Published
- Jun 3, 2026
- Updated
- Aug 14, 2026
- Reserved
- Mar 12, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.0 | 9.1 Critical | CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L | @huntr_ai |
| 3.1 | 7.7 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N | redhat-SADP |
Weaknesses
- CWE-201 Insertion of Sensitive Information Into Sent Data
Affected Products
| Product | Versions |
|---|---|
mlflow/mlflowmlflow |
|
References
- https://huntr.com/bounties/f8e591a0-0f19-4910-b82e-16c9956f2233
- https://github.com/mlflow/mlflow/commit/4a3f2f720cb4f058c9e0c5b883e0acc9ab64a7f3
- https://access.redhat.com/security/cve/CVE-2026-4035vdb-entry
- RHBZ#2484318issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4035.json
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