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CVE-2026-1166929.8Critical

MLflow: Remote code execution on unauthenticated MLflow servers via third-party scorer deserialization importing caller-placed artifact modules

mlflow

Not in CISA KEV
0.7%probability of exploitation in the next 30 days
53rd percentile
050100

Higher than 53% of scored CVEs

9.8CriticalCVSS
LowCrit.

DescriptionNVD

MLflow is an open source AI engineering platform for agents, large language models, and machine learning models. From 3.12.0rc0 until 3.17.0, third-party scorer deserialization in mlflow/genai/scorers/base.py accepts request-selected descendants of THIRD_PARTY_SCORER_ALLOWED_MODULES rather than requiring an exact allowed module. A caller can use MLflow artifact endpoints to place a Python module beneath a writable allowed package and submit its module and class through /ajax-api/3.0/mlflow/scorer/invoke. Scorer.model_validate_json() imports the module and constructs the class before trace processing. Authentication-disabled deployments permit this code execution without credentials, while basic-auth deployments require a principal capable of creating an experiment and run and uploading artifacts. In either configuration, the allowed scorer package must be writable by the server process. This issue is fixed in version 3.17.0.

Coverage1 article · 1 outlet

First in our coverage: SecurityOnline, 28 Oct.

  1. Attackers exploit MLflow file read flaw as PoC code emerges
    SecurityOnline · first in our coverage · mentions it in passing

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References

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