Claude Code echo command allowed bypass of user approval prompt for command execution

Claude Code has a flaw that lets attackers run commands without getting permission from the user. An attacker needs to insert malicious content into the chat, and the tool will execute their command without asking for approval first.

CWE-78 command injection vulnerability in Claude Code versions <1.0.20 allows bypass of user confirmation prompts through a command parsing error. Attack vector requires injecting untrusted content into the context window; impact is arbitrary command execution with user privileges without explicit approval.