The 49ers are placing cornerback Richard Sherman on injured reserve with a leg injury, as Mike Garafolo of NFL.com tweets. He’ll be sidelined for at least three weeks, but Ian Rapoport of NFL.com (Twitter link) adds that it’s a short-term issue, meaning that he should be able to return later this year. 
The exact nature of Sherman’s injury is not clear, especially since he finished out the season opener against the Cardinals. At minimum, he’ll miss the next three games against the Jets, Giants, and Eagles.
Sherman, 32, is in his contract year, and he says he’s hoping to play four more years. Set to make $8MM in base salary this year, he’s hoping to secure his next/final pay day with a big 2020. In 2019, Sherman earned Pro Bowl and second-team All-Pro honors while helping the 49ers reach the Super Bowl. In the regular season, he notched three interceptions and 61 total stops in 15 starts.
The Niners have Jason Verrett and Ahkello Witherspoon on hand to step in at outside corner. Now, they’ll also have an available roster spot to add another CB for depth.
I believe Witherspoon is hurt too.