Exploiting a decade-old flaw, hackers are taking control of dormant Twitter accounts to spread Islamic State (IS) propaganda, a media report said.
Some of these accounts are tweeting messages supporting violence.
To take control of the accounts that have remained inactive for years, hackers are exploiting Twitter's legacy lack of email confirmation, the report said.
Twitter introduced the requirement of confirming new accounts through an email address or phone number in June, but many older accounts still remain unconfirmed.
As many of the email addresses that were used to register these accounts either did not exist or expired long ago, hackers are taking control of these accounts simply by creating these email addresses.
Twitter said it was trying to find a solution to the problem.
"Reusing email addresses in this manner is not a new issue for Twitter or other online services," a Twitter spokesperson told TechCrunch.
"For our part, our teams are aware and are working to identify solutions that can help keep Twitter accounts safe and secure," the spokesperson was quoted as saying.
Since August 2015, Twitter has removed over 1.2 million accounts that promoted terrorism.