Those two actives players are left tackle Joe Staley (concussion) and, for the first time this season, running back Brandon Jacobs, who has been sidelined since the preseason because of a left knee injury.
Wide receiver Mario Manningham is inactive because of a shoulder injury he suffered during last week's loss to the New York Giants. Randy Moss is listed as a starting wide receiver for San Francisco, along with Michael Crabtree.
All of the Seahawks' starters are active.
The Associated Press contributed to this report.