MLflow: Unauthenticated full-read SSRF in webhook delivery: _validate_webhook_url bypassed via…
MLflow
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- Severity
- Critical, CVSS 9.3
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
- Record
- CVE-2026-64849
- Affects
- MLflow
- Known exploited
- Yes, listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- August 17, 2026
- Source last modified
- October 26, 2026
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.
Description quoted from the NVD record.
Who is affected
Your organization is affected if it runs MLflow, made by LF Projects, an open source platform that teams use to build, track and manage AI and machine learning models. This flaw affects versions 3.3.0 up to, but not including, 3.15.0. It sits in the feature that tests webhooks (automatic messages MLflow sends to other web services), which anyone can use without logging in. An attacker could make your MLflow server reach internal systems or cloud server information services that should be private, and read back their replies. This flaw is rated Critical. It is on CISA's Known Exploited Vulnerabilities list, which means attacks using it have been seen.
What to do
- If your organization installed and runs MLflow itself, the person who looks after it should check which version is in use.
- If it is version
3.3.0or later but before3.15.0, that person should update MLflow to version3.15.0or later, which fixes this flaw. - Do this update as soon as possible, because attacks using this flaw have been seen.
- If an IT provider or vendor runs MLflow for your organization, send them this advisory and ask when the update will be done.
Analysis written from the source record as of October 26, 2026 and reviewed before publishing.