My exterior recessed light socket is rusted. How do I replace just the socket in the stucco ceiling?

Rusted sockets in exterior recessed lights mean moisture has penetrated the fixture. You typically replace the entire trim or housing, not just the socket. This is a full fixture replacement involving line voltage. If you are not comfortable with electrical work or sealing penetrations in stucco, hire a licensed electrician. They will ensure a weather-tight, code-compliant installation.