2,173. The Prohibited Relations of a Servant

Hilchos Issurei Biah 14:17

A servant while in his servitude is permitted to marry his mother, daughter, sister, etc. Since he is no longer considered a non-Jew, the relationships that were previously prohibited to him are now permitted; since he has not yet become Jewish, the relationships that are prohibited to converts are not yet prohibited.

Hilchos Issurei Biah 14:18

The Rambam opines that if a servant engages in relations with another man or with an animal, he is liable to execution because these are universal prohibitions.