A hacker who goes by the alias Tessa88@exploit.im claims to have stolen more than 32 million Twitter login credentials. These credentials are now being sold on the dark web, according to LeakedSource.

However, a Twitter spokesman has denied this report, saying to The Huffington Post: “We are confident that these usernames and credentials were not obtained by a Twitter data breach – our systems have not been breached. In fact, we’ve been working to help keep accounts protected by checking our data against what’s been shared from recent other password leaks.”

To see if your details were possibly leaked, you can check LeakedSource’s database. If there, it is probably safest to change your password and, if you use that password across multiple sites, change those as well.

According to LeakedSource, the Twitter breach is probably malware that infected some browsers. This data set includes 32,888,300 records and “each record may contain an email address, a username, sometimes a second email and a visible password.”

The site added: “We have very strong evidence that Twitter was not hacked, rather the consumer was. These credentials however are real and valid. Out of 15 users we asked, all 15 verified their passwords.”

Other major tech hacks in recent years include Myspace with 360 million accounts compromised and Linkedin with 117 million emails and passwords hacked.