MLflow vulnerable to remote code execution on unauthenticated servers via third-party scorer deserialization importing caller-placed artifact modules

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-116692: 0.70% estimated exploitation activity in the next 30 days; percentile 53.37 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary MLflow 3.12.0 introduced registration and deserialization support for third-party scorers in OSS MLflow. During scorer deserialization, the server accepts a request-controlled Python module path beneath one of four allowed package prefixes, imports that module, obtains a request-controlled class, and instantiates it synchronously. An HTTP caller can combine this behavior with MLflow's built-in experiment, run, and artifact-upload endpoints: 1. Create an experiment whose local artifact location points to a writable allowed scorer package. 2. Create a run, causing MLflow to allocate ` / /artifacts/`. 3. Upload a Python module into that run artifact directory. 4. Submit a serialized third-party scorer whose module path resolves to the uploaded file. 5. Trigger server-side import and class construction through `/ajax-api/3.0/mlflow/scorer/invoke`. On the default no-auth server using the official MLflow v3.14.0 image, this produces unauthenticated arbitrary Python code…

Published by the source

27 Oct 2026, 21:26 UTC

Last modified by the source

27 Oct 2026, 21:30 UTC

Source last checked

28 Oct 2026, 06:05 UTC

1. Revision 2 · amended · 28 Oct 2026

   Amended from osv record GHSA-26p8-2jq9-3vq9

2. Revision 1 · created · 27 Oct 2026

   Published from ghsa record GHSA-26p8-2jq9-3vq9

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# Patch Next advisory brief: CVE-2026-116692

Advisory: MLflow vulnerable to remote code execution on unauthenticated servers via third-party scorer deserialization importing caller-placed artifact modules
IDs: CVE-2026-116692, GHSA-26p8-2jq9-3vq9
Record: https://patchnext.com/advisories/cve-2026-116692 (revision 2, source checked 28 Oct 2026, 06:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mlflow 3.17.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI mlflow: affected >= 3.12.0rc0, < 3.17.0; fixed in 3.17.0

## Suggested inspection (read-only)
- `python -m pip show mlflow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mlflow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-26p8-2jq9-3vq9 (OSV record GHSA-26p8-2jq9-3vq9 lists affected ranges: PyPI mlflow >=3.12.0rc0 <3.17.0 (fixed))
- Verified: https://github.com/advisories/GHSA-26p8-2jq9-3vq9 (GitHub-reviewed advisory GHSA-26p8-2jq9-3vq9 lists affected ranges: PyPI mlflow >=3.12.0rc0 <3.17.0)

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