CVE-2026-28500: ONNX Untrusted Model Repository Warnings Suppressed by silent=True in onnx.hub.load() — Silent Supply-Chain Attack

Summary

A security control bypass exists in onnx.hub.load() due to improper logic in the repository trust verification mechanism. While the function is designed to warn users when loading models from non-official sources, the use of the silent=True parameter completely suppresses all security warnings and confirmation prompts. The Technical Flaw The vulnerability is located in onnx/hub.py. The security gate uses a short-circuit evaluation that prioritizes the "silent" preference over the trust requirement: Python if not verifyreporef(repo) and not silent: # This block (Warning + User Input) is SKIPPED if silent=True print("The model repo... is not trusted") if input().lower() != "y": return None Key Points of Failure: Complete Suppression: If a developer or a third-party library sets silent=True, the application will download and execute models from any attacker-controlled GitHub repository without notifying the user. Integrity Verification Bypass: The SHA256 integrity check validates the model against a manifest file. Since the attacker controls the repository, they also control the manifest, allowing them to provide a "valid" hash for a malicious model. Impact This vulnerability transforms a standard model-loading function into a vector for Zero-Interaction Supply-Chain Attacks. When chained with file-system vulnerabilities , an attacker can silently exfiltrate sensitive files ( SSH keys, cloud credentials) from the victim's machine the moment the model is loaded.