Sep 2026: Windows ML CLI: CORS misconfig enables localhost RCE
CVE-2026-84452 Published on September 2, 2026
Windows ML CLI: CORS misconfig enables localhost RCE
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.
Vulnerability Analysis
CVE-2026-84452 is exploitable with network access. This vulnerability is considered to have a low attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-84452. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Types
Permissive Cross-domain Policy with Untrusted Domains
The software uses a cross-domain policy file that includes domains that should not be trusted.
Missing Authentication for Critical Function
The software does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.