Brown (ankle) has been ruled out for the rest of Sunday's game against the 49ers, Matt Maiocco of NBC Sports Bay Area reports.
Brown injured his ankle in the first half, and, after he was evaluated by medical staff, it's been determined that the injury is severe enough for him to miss the rest of Sunday's game. With Xavier Woods (hamstring) also ruled out, Kendell Brooks will continue to work in an expanded role at safety.