CVE-2026-64849
MLflow Server-Side Request Forgery Vulnerability
MLflow MLflow
MLflow is an open source AI engineering platform for agents, large language models, and machine learning models. 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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 19 August 2026. US federal agencies were required to remediate it by 2 September 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 16.4%, which is higher than 96.8% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Frequently asked questions
Is CVE-2026-64849 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-64849.
What does CVE-2026-64849 affect?
CVE-2026-64849 affects MLflow MLflow. MLflow is an open source AI engineering platform for agents, large language models, and machine learning models. 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.
How severe is CVE-2026-64849?
CVE-2026-64849 is rated CRITICAL with a CVSS base score of 9.3. EPSS puts the probability of exploitation in the next 30 days at 16.4%, higher than 96.8% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 2 September 2026.
How should organisations respond to CVE-2026-64849?
Apply the vendor patch for MLflow MLflow as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.