China’s powerful internet regulator is conducting a security review of Shein as the fast-fashion giant gears up for its highly anticipated U.S. initial public offering, CNBC has learned.

The Cyberspace Administration of China is reviewing Shein’s supply chain presence in the country, where the bulk of its manufacturers and suppliers are located, a person familiar with the matter told CNBC.

The review focuses on how Shein handles information about its employees, partners and suppliers in the region, The Wall Street Journal reported. The CAC is also examining whether Shein can ensure that data doesn’t get leaked overseas, according to the Journal.