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CVE-2026-64849: MLflow Server-Side Request Forgery Vulnerability

CVE-2026-64849 is rated critical with a CVSS v3.1 base score of 9.3 and affects MLflow MLflow. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-08-19, which means exploitation in the wild has been observed.

Vulnerability description

MLflow is an open source AI engineering platform for agents, large language models, and machine learning models. Starting in 3.3.0 and prior to 3.15.0, the unauthenticated POST /api/2.0/mlflow/webhooks/{id}/test endpoint calls _validate_webhook_url() in mlflow/utils/validation.py only for the original URL while mlflow/webhooks/delivery.py follows redirects and re-resolves the hostname without pinning the validated address, allowing attackers to reach internal or cloud metadata services and receive response_status and response_body. This issue is fixed in version 3.15.0.

Severity breakdown

CVSS v3.1 9.3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: Low. Some data can be modified.
  • Availability impact: None. No effect on availability.

Underlying weakness

CWE-918: Server-Side Request Forgery

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Affected products

  • Lfprojects Mlflow: from 3.3.0 before 3.15.0

References