Cardiff City are also keen on taking Mendy to the Premier League, while Lyon are looking to keep the France U-19 international in his homeland.
"Nothing has been sorted with any club," Mendy's agent, Sylvain Chavanon, told L'Equipe.
"Sunderland are one of the teams that we are in talks with.
"There is also Lyon. Cardiff have spoken with us, but we don't have any news at the moment."