Claude Code vulnerable to command execution prior to startup trust dialog

Claude Code could execute malicious code from a project before asking the user for permission, if the project used Yarn 3.0 or later. An attacker could trick a user into opening an untrusted project folder to run harmful commands.

Claude Code versions prior to 1.0.39 fail to validate startup trust before loading Yarn 3.0+ plugins, allowing arbitrary code execution through plugin mechanisms. The attack requires user interaction (opening a malicious project directory) and specific Yarn version presence; the vulnerability bypasses the trust dialog that should gate code execution.