Researchers have discovered a critical 55-year-old vulnerability, dubbed Terminal2Shell, that affects every major operating system, including macOS, Windows, and Linux, allowing anyone with local access and a working keyboard to obtain instant, fully interactive shell access with no additional authentication required. The design-level flaw in terminal emulators enables attackers to issue arbitrary commands with the full privileges of the logged-in user, potentially leading to file deletion, software installation, and system configuration modifications. Exploitation is trivial, requiring no special tools, and a working proof of concept has been released, with no patch currently available to fix the issue, leaving users to rely on mitigations such as closing terminals immediately after use or restricting keyboard access.