Systemic Flaw in MCP Protocol Could Expose 150 Million Downloads

**Critical MCP protocol vulnerability enables arbitrary command execution and potential data exposure:** Ox Security reported an architectural flaw in Anthropic's Model Context Protocol (MCP) STDIO execution model that can execute attacker-supplied commands even when a launched process fails, potentially leading to full system takeover, exposure of sensitive data (API keys, chat histories, internal databases), and broad supply-chain impact across hundreds of projects and up to ~200,000 vulnerable instances; Anthropic has characterized the behavior as "by design" and declined to change the protocol.