The Twitter website is being widely exploited by users who have stumbled across a flaw which allows messages to pop-up and third-party websites to open in your browser just by moving your mouse over a link.
Thousands of Twitter accounts have posted messages exploiting the flaw. Victims include Sarah Brown, wife of the former British Prime Minister.
It appears that in Sarah Brown's case her Twitter page has been messed with in an attempt to redirect visitors to a hardcore porn site based in Japan. That's obviously bad news for her followers - over one million of them.
It looks like many users are currently using the flaw for fun and games, but there is obviously the potential for cybercriminals to redirect users to third-party websites containing malicious code, or for spam advertising pop-ups to be displayed.