Tennis star Rafael Nadal and gymnast Laurie Hernandez are among the latest athletes exposed in the latest leak of confidential medical documents.
The World Anti-Doping Agency has said three previous hacks were led by a group of Russian hackers.
Fancy Bears, the hackers, reportedly have gained access to WADA's anti-doping administration and management system through an IOC-created account for the 2016 Olympics in Rio de Janeiro.
The leaked data has revealed therapeutic use exemptions for several Olympic stars including Simone Biles, Chris Froome and Serena Williams. TUEs are granted for athletes to take banned substances for approved medical needs. None of the athletes have broken any rules.
The latest leak shows that Nadal was granted exemptions in 2009 and 2012. The 14-time Grand Slam winner is coming off a gold medal in the men's doubles with Marc Lopez. Earlier in the year, Nadal missed more than two months of action as he nursed a wrist injury.
Hernandez, a member of the gold-medal winning women's all-around team, was granted a TUE for methylprednisolone, which is used to treat conditions such as allergies, arthritis, lupus and ulcerative colitis.
The latest leak also showed TUEs for several Olympic medalists in track and field including Great Britain's Mo Farah and Burundi's Francine Niyonsaba. Farah, the two-time Olympic champion at 5,000 and 10,000 meters, received a TUE for intravenous infusions of saline solution, morphine sulphate and vicodin (oral administration) in 2014 after he collapsed during a training session. He had no active TUEs in Rio de Janeiro, according to the Fancy Bears data.