CVE-2026-4035

Summary

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 Software

Weaknesses

• CWE-201: CWE-201 Insertion of Sensitive Information Into Sent Data

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: partial

Additional References

• https://huntr.com/bounties/f8e591a0-0f19-4910-b82e-16c9956f2233

python-mlflow: MLflow: Sensitive credential exfiltration via environment variable resolution in AI Gateway secrets

Additional References

• https://access.redhat.com/security/cve/CVE-2026-4035
• https://bugzilla.redhat.com/show_bug.cgi?id=2484318
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4035.json

References

• https://huntr.com/bounties/f8e591a0-0f19-4910-b82e-16c9956f2233
• https://github.com/mlflow/mlflow/commit/4a3f2f720cb4f058c9e0c5b883e0acc9ab64a7f3

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