MLFlow Creates a Temporary File With Insecure Permissions
In mlflow/mlflow versions prior to 3.11.0, the get_or_create_nfs_tmp_dir() function in mlflow/utils/file_utils.py creates temporary directories with world-writable permissions (0o777), and the _create_model_downloading_tmp_dir() function in mlflow/pyfunc/__init__.py creates directories with group-writable permissions (0o770). These insecure permissions allow local attackers to tamper with model artifacts, such as cloudpickle-serialized Python objects, and achieve arbitrary code execution when the tampered artifacts are deserialized via cloudpickle.load(). This vulnerability is particularly critical in environments with shared NFS mounts, such as Databricks, where NFS is enabled by default. The issue is a continuation of the vulnerability class addressed in CVE-2025-10279, which was only partially fixed.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | mlflow | >= 1.26.0, < 3.11.0 | 3.11.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-4137
- https://github.com/mlflow/mlflow/commit/1dcbb0c2fbd1f446c328830e601ca13a28219b8a
- https://github.com/advisories/GHSA-4x5p-f36r-mxxr
- https://github.com/mlflow/mlflow
- https://huntr.com/bounties/648dc30b-76c7-4433-86b8-f43d926fd8d6
- https://pypi.org/project/mlflow
- https://github.com/advisories/GHSA-f2m9-wcf4-cwwx
- https://github.com/mlflow/mlflow/commit/bd8854fb2b4b168a4384ebddc6c4a0b5d56aff01
- https://github.com/pypa/advisory-database/tree/main/vulns/mlflow/PYSEC-2026-2655.yaml
- CVSS vector
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-378- Platform
- Python (PyPI)
- Package
mlflow- Disclosed
- 18.05.2026
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-2655 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-f2m9-wcf4-cwwx - CC BY 4.0
Vulnerability history: mlflow
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 82
- First → latest
- 02.2022 09.2026
- Without a fix
- 18
- Exploited in attacks
- 1
Severity breakdown
- Critical 20
- High 48
- Medium 13
- Low 1
Disclosures per year
- 2022: 1
- 2023: 22
- 2024: 24
- 2025: 8
- 2026: 27
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