Short video app TikTok has taken measures to stop a cyberattack targeting several brand and celebrity accounts, including news network CNN, a spokesperson for the company said on Tuesday.

“We have been collaborating closely with CNN to restore account access and implement enhanced security measures to safeguard their account moving forward,” the spokesperson said.

TikTok said that the number of accounts compromised is “very small” and it is working with affected account owners to restore access if needed.

A source at TikTok told Reuters the account of reality TV star Paris Hilton was targeted but had not been compromised.

TikTok parent company ByteDance is currently challenging a law in courts that requires it to sell TikTok by next January or face a ban in the country. The White House said it wants to see Chinese-based ownership ended on national security grounds.

TikTok has argued it will not share U.S. user data with the Chinese government and that it has taken substantial measures to protect the privacy of its users.