The fight is tentatively scheduled to be held in Los Angeles, but neither an official date nor venue has been set.
Lombard, who signed with UFC on April 25, is riding a 25-fight win streak, improving his professional record to 31-2-1 with one no-contest.
He possesses exceptional punching power and submission skills, having finished 12 of his 15 most recent opponents.
A black belt in judo and Brazilian jiu-jitsu, Lombard, 34, represented Cuba as a judoka in the 2000 Olympics.
The power-punching Stann will enter the cage with a professional mark of 12-4. He is 3-1 in his four most recent fights, with each of his wins coming by knockout.
The 31-year-old former WEC light heavyweight champion has compiled a 4-1 record since moving to 185 pounds.