Hackers claim to have obtained information relating to the likes of American tennis stars Serena and Venus Williams and four-time 2016 gymnastics gold medallist Simone Biles in a move the US Anti-Doping chief Travis T Tygart has condemned as "cowardly and despicable".
WADA revealed on Tuesday that hackers had illegally gained access to its anti-doping administration and management system (ADAMS) database via an IOC-created account for the Rio Games.
The database contained information on exemptions athletes were given to take banned substances to treat medical conditions.
Venus Williams said she was "disappointed" that her medical data has been "compromised by hackers and published without...permission".
Speaking about Biles, Steve Penny, president of USA Gymnastics, said: "Simone has filed the proper paperwork per USADA and WADA (World Anti-Doping Agency) requirements and there is no violation.
The International Gymnastics Federation, the United States Olympic Committee and USADA have confirmed this."
Biles herself took to Twitter to explain her condition and why it requires her to take medication.
Tygart backed up the athletes, saying: "In each of the situations, the athlete has done everything right in adhering to the global rules for obtaining permission to use a needed medication.
"The respective international federations through the proper process granted the permission and it was recognised by the the IOC (International Olympic Committee) and USADA.
"The cyber-bullying of innocent athletes being engaged in by these hackers is cowardly and despicable. It is time for the entire international community to stand up and condemn this cyber-attack on clean sport and athletes' rights."
Cyber espionage group Tsar Team (APT28), which is also known as Fancy Bears, is said to have accessed information concerning substances for which athletes have sought and received therapeutic use exemption (TUE).
The attacks are understood to have originated in Russia in the wake of the McLaren Report, which uncovered a state-sponsored doping programme and led to some competitors being banned from this summer's Olympic Games and the blanket exclusion of the country's athletes at the ongoing Paralympics.