A CRITICAL-severity vulnerability identified as CVE-2026-4035 has been published on June 3, 2026 with a CVSS base score of 9.1. This security advisory provides a detailed breakdown of the vulnerability, its potential impact, weakness classification, and actionable steps to protect your systems.
Vulnerability Details
CVE ID: CVE-2026-4035
Severity: CRITICAL
CVSS Score: 9.1
Published: June 3, 2026
Weakness (CWE): CWE-201
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | None |
| Confidentiality Impact | High |
| Integrity Impact | Low |
| Availability Impact | Low |
Technical 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.
Potential Impact
If exploited, this critical-severity vulnerability could allow an attacker to compromise sensitive data confidentiality. Organizations running affected software should treat this as a priority remediation item.
Recommended Action
No official patch is available yet. Until one is released:
- Monitor the official NVD page and vendor channels for patch announcements.
- Restrict access to the affected system or service where possible.
- Apply network-level mitigations such as firewall rules or WAF policies.
- Enable logging and alerting for anomalous activity related to this vulnerability.
- Review your incident response plan in case of active exploitation.
References
Related Security Advisories
- [CRITICAL] CVE-2026-3655 — CVSS 9.8 (May 29, 2026) — CRITICAL / CVSS 9.8
- [CRITICAL] CVE-2026-9059 — CVSS 9.3 (May 20, 2026) — CRITICAL / CVSS 9.3
- [CRITICAL] CVE-2026-5229 — CVSS 9.8 (May 15, 2026) — CRITICAL / CVSS 9.8
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