GHSA-3x77-wg38-92r3: mcp-shell has a Secure Mode Allowlist Bypass via Default `/bin/bash` Executable

mcp-shell has a security flaw where its default configuration allows `/bin/bash` as an allowed command, but the validator only checks the first word of a command and ignores flags like `-c`. This means an attacker can send `/bin/bash -c <any-command>` to bypass the allowlist (a restrictions list) and run any command on the system, such as `id` or `curl`, with no authentication needed.