Claims about the size and scope of the breach initially varied with early accounts in December saying 400m email addresses and phone numbers were stolen.
Email addresses of more than 200 million Twitter users have been reportedly stolen and leaked by hackers.
The emails were posted on an online hacking forum, a security researcher has revealed.
The breach “will unfortunately lead to a lot of hacking, targeted phishing and doxxing”, Alon Gal, co-founder of Israeli cybersecurity monitoring firm Hudson Rock, wrote on LinkedIn. He called it “one of the most significant leaks I’ve seen”.
Twitter has not commented on the report, which Gal first posted about on social media on 24 December, nor responded to inquiries about the breach since that date. It was not clear what action Twitter has taken to investigate the issue.
xaScreenshots of the hacker forum, where the data appeared on Wednesday, have circulated online.
Troy Hunt, creator of breach notification site Have I Been Pwned, viewed the leaked data and said on Twitter that it seemed “pretty much what it’s been described as”.
There were no clues to the identity or location of the hacker or hackers behind the breach. It may have taken place as early as 2021, which was before Elon Musk took over ownership of the company last year.
Claims about the size and scope of the breach initially varied with early accounts in December saying 400m email addresses and phone numbers were stolen.
A major breach at Twitter may be of interest to the US Federal Trade Commission who have been monitoring the Elon Musk-owned company for compliance with European data protection rules and a US consent order for months.