SANTA CLARA >> Safety Talanoa Hufanga is cleared to return to the 49ers’ embattled defense as soon as today’s game against the Chicago Bears.

Missing from that defense for a third straight game, however, will be defensive end Nick Bosa, who was downgraded to out on Saturday because of a lingering oblique injury. Bosa has not practiced the past three weeks, nor has left tackle Trent Williams, who was ruled out Friday by the 49ers (5-7).

Left guard Aaron Banks will miss a second straight game because of a concussion, being downgraded from questionable to out.

While Hufanga was officially activated off the injured reserve list, the 49ers moved running back Jordan Mason (ankle) and special teams ace George Odum (knee) onto IR.

Hufanga, a 2022 All-Pro, has played in only two games this season: the Week 3 loss at the Los Angeles Rams upon his recovery from anterior cruciate ligament repair, and just 11 snaps into the Week 5 loss against the Arizona Cardinals before exiting with torn wrist ligaments.

Hufanga’s return to practice brought much needed energy, as did that of linebacker Dre Greenlaw, who is expected to be activated off Injured Reserve for Thursday’s game against the Rams.

Hufanga is expected to play with a protective cast over his right wrist.

As for reinforcements, the 49ers promoted offensive lineman Sebastian Gutierrez to the active roster from the practice squad, from where running back Ke’Shawn Vaughn and linebacker Jalen Graham were elevated Saturday.

Vaughn adds depth to a running back unit led by probable first-time starter Isaac Guerendo, Patrick Taylor Jr. and Israel Abanikanda, in the wake of last Sunday’s injuries to Mason and Christian McCaffrey (knee; Injured Reserve).