Kirk (knee) was limited in Wednesday's practice, Sam Warren of The Athletic reports.
It's a new injury for Kirk, who made his season debut in Week 7 against the Falcons after missing the first six games with a calf injury. The Niners are coming off their bye and are hoping to get some reinforcements at wide receiver, with Demarcus Robinson (ankle) limited Wednesday while Mike Evans (ribs/Achilles) and Deebo Samuel (hamstring) logged DNPs.