New Vulnerability in GitHub Copilot and Cursor: How Hackers Can Weaponize Code Agents

Pillar Security reports a novel supply-chain attack named "Rules File Backdoor" in which adversaries hide malicious instructions inside AI coding assistants' rule/configuration files (using invisible Unicode and prompt-engineering techniques) to covertly cause tools like Cursor and GitHub Copilot to generate vulnerable or backdoored code; the report includes technical details, PoC demonstrations, mitigation recommendations, and a responsible-disclosure timeline with vendor responses.