Facebook disclosed last Friday that 50 million accounts had been breached, and forcibly logged out 90 million affected users. It appears the hackers could have accessed sensitive profile information, purchase histories and private messages. Most disturbingly, since Facebook logins can be used on other sites, companies using that Facebook Connect feature are now rushing to figure out whether their sites were breached.
Why it matters: Single-sign-on login systems do not make a hack more likely. But they do affect what a hacker can access from inside a system. While Facebook reports there is no evidence third-party apps were accessed, this incident should cause consumers to re-evaluate whether to link accounts in the first place.