# CVE-2026-84452: Windows ML CLI: CORS misconfig enables localhost RCE

> A malicious website can trigger arbitrary code execution in Windows ML CLI via a CORS misconfiguration and unvalidated trust_remote_code parameter.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Sep 2026
- **Updated:** 3 Sep 2026
- **Also known as:** GHSA-96p9-rh4f-92cf, PYSEC-2026-3944

## What is CVE-2026-84452?

CVE-2026-84452 is a high-severity code injection vulnerability in microsoft winml-cli, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Windows ML CLI is a command line tool for building portable, performant, and high-quality AI models for Windows ML. Prior to 0.4.0, the src/winml/modelkit/serve/cli_api.py component exposes WinML CLI commands through a localhost HTTP API without authentication and configures the allow_origins setting as a wildcard in both src/winml/modelkit/serve/cli_api.py and src/winml/modelkit/serve/app.py. A malicious website loaded by a user can send cross-origin requests to /v1/cli/build or /v1/cli/config and set the trust_remote_code parameter to true, which is converted to the --trust-remote-code command-line flag without validation. This reaches AutoConfig.from_pretrained with trust_remote_code=True in src/winml/modelkit/loader/_autoconfig.py and imports Python code from an attacker-controlled model repository, resulting in arbitrary code execution as the server user. This issue is fixed in version 0.4.0.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-84452?

3 open source packages ship an affected version, including winml-cli.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `winml-cli` | PyPI | All versions | 0.4.0 |
| `winml-cli` | PyPI | All versions | 0.4.0 |
| `winml-cli` | PyPI | All versions | 0.4.0 |

## How do I fix CVE-2026-84452?

Upgrade winml-cli to 0.4.0 or later.

## Is CVE-2026-84452 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84452 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84452 and fix it if it is affected.

What it is: CVE-2026-84452 is a high-severity code injection vulnerability in microsoft winml-cli, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84452 exists.

Affected packages and fixed versions:
- winml-cli (PyPI): affected all versions; fixed in 0.4.0
- winml-cli (PyPI): affected all versions; fixed in 0.4.0
- winml-cli (PyPI): affected all versions; fixed in 0.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84452/ (Markdown: https://insights.sbomify.com/CVE-2026-84452/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84452
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84452
- OSV: https://osv.dev/vulnerability/CVE-2026-84452

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84452/
Summaries are generated and may contain mistakes; the official description above is the record.