One fifth of Facebook users are exposed to malware contained in their news feeds, claim security researchers.
Security firm BitDefender said it had detected infections contained in the news feeds of around 20% of Facebook users.
By clicking on infected links in a news feed, users risk having viruses installed on their computer.
Facebook said it already had steps in place to identify and remove malware-containing links.
BitDefender arrived at its figures by analysing data from 14,000 Facebook users that had installed a security app, called safego, it makes for the social network site.
In the month since safego launched, it has analysed 17 million Facebook posts, said BitDefender.