GHSA-74hp-mggr-hv58: mcp-shell has a Secure Mode Allowlist Bypass via Git Shell Alias

mcp-shell's secure mode is supposed to restrict which programs can run, but it has a bypass vulnerability. An attacker can use a Git feature (shell aliases, triggered by the `!` character) to run any command they want, even though the security checker blocks other dangerous characters. The default Docker setup runs this vulnerable version without protection, so anyone who can send commands can take over the system.