Data containing the email addresses of more than 200mln Twitter Inc (NYSE:TWTR) users is being leaked on a hacker forum, according to reports.
Cyber-crime information firm Hudson Rock spotted the leak and said the threat was “significant”.
The stolen information includes email addresses to set up accounts, which will worry anonymous users.
Alon Gal of Hudson Rock told the BBC the leak “would, unfortunately, lead to a lot of accounts getting hacked, targeted with phishing or doxed”.
According to the tech news website Bleeping Computer, which has downloaded the content from the hacking forum, many of the listed email addresses were corrected, although there were some duplicates.
Another researcher, according to the BBC, suggested that many Twitter accounts were featured several times, but there were still 100mln unique email addresses.