Is it safe to eat smoked brisket left out all night?

No, it is not safe to eat smoked brisket that has been left out all night. Perishable food should not be left at room temperature for more than two hours, as bacteria can grow quickly in the "danger zone" between 40°F and 140°F. Consuming food that has been left out for an extended period can lead to foodborne illnesses. It's best to discard it to ensure safety.