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, if any, Twitter has taken to investigate or remediate the issue.
