MLflow AI Gateway environment variable secret exfiltration
CVE-2026-4035 affects mlflow/mlflow versions prior to 3.11.0. In vulnerable versions, the AI Gateway secret configuration permits the api_key field to contain $ENV_VAR references. At runtime, MLflow resolves those references against the MLflow server's own environment and then includes the resolved value in provider authentication headers sent to the configured upstream api_base. An attacker who can configure gateway secrets and direct requests to an attacker-controlled upstream endpoint can therefore cause MLflow to disclose sensitive server-side environment variables, including credentials such as AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY. The issue is exploitable by low-privileged authenticated users in deployments using basic-auth, and by unauthenticated users in default deployments without basic-auth.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
api_base endpoints. Where possible, avoid storing highly sensitive credentials in environment variables accessible to the MLflow server, and monitor outbound requests from MLflow for unexpected upstream destinations. If exposure is suspected, rotate affected credentials immediately.Remediation
Patch, then assume compromise.
4a3f2f720cb4f058c9e0c5b883e0acc9ab64a7f3. After upgrading, review AI Gateway configurations for untrusted upstream api_base values and rotate any environment-based credentials that may have been exposed.Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.