TikTok says it is addressing a cyber-attack that targeted brands and celebrities, including Paris Hilton and CNN.
However, the video-sharing app told the BBC that a “very limited” number of accounts had been compromised.
It added that it was working with users to restore access to their accounts.
TikTok, which is owned by Chinese company ByteDance, did not share further details on cyber-attack, such as how it was carried out.
A TikTok spokesperson said Ms Hilton’s account was targeted, but it was not compromised.
The reality TV star, who has more than 10 million followers on TikTok, is an active user of the platform.
The account of news broadcaster CNN has been compromised, however.
“We have been collaborating closely with CNN to restore account access and implement enhanced security measures to safeguard their account moving forward,” TikTok said.
“We are dedicated to maintaining the integrity of the platform and will continue to monitor for any further inauthentic activity.”
CNN did not immediately respond to a BBC request for comment.
The news comes as TikTok is facing a ban in the US, unless it is sold by its Chinese parent company.
TikTok has millions of users worldwide, but has faced questions over the security of users’ data and its links to the government in Beijing.
It is also emerging as a new social media battleground for the US elections.
Earlier this month, Donald Trump joined TikTok, despite attempting to ban it on national security grounds during his presidency.
Trump, who has amassed more than five million followers since launching his account on Saturday, said he will use “every tool available to speak directly with the American people”.
President Joe Biden is also using the platform to campaign for re-election in November, but he has only picked up around 350,000 followers – far fewer than his rival.