Pauline reported Thursday that Moreau underwent surgery and will need four to six months to recover and will be at "full strength" by early-to-mid August.
NFL Network's Omar Ruiz first reported the injury at the pro day.
The injury occurred while Moreau was bench-pressing, and he described it to Ruiz as a "little strain."
Chase Goodbread of NFL.com noted Moreau cut his workout short after suffering the injury and was expected to meet with the UCLA medical staff.
Bruins head coach Jim Mora didn't see the setback as serious, per Goodbread: "It's being evaluated. I don't think it's anything serious. ... And all these teams that are really interested in him will be back to see him in an individual workout as well. So anything that happened to him I believe is minor and nothing to worry about."
This is not the first time Moreau suffered an injury in his career. He played just three games in the 2015 season because of a Lisfranc injury in his left foot. However, he impressed in 2016 with 31 total tackles, two interceptions and eight passes defended.
Moreau's speed immediately stands out, and his NFL.com draft profile listed his 40-yard-dash time at 4.35 seconds. He should be able to keep up with most NFL receivers at that speed, and it will also allow him to make up space downfield should he be beaten at the line of scrimmage.
Bleacher Report's Matt Miller projected the Miami Dolphins to select Moreau with the No. 54 overall pick in his most recent mock draft.