Around 4 p.m. Pacific Time, the websites operated by at least 35 companies, including ABC, CNN, Gawker, Hulu, Pinterest, Reddit and Yahoo, began redirecting online visitors to a Facebook error page.
Facebook has acknowledged the problem and says that everything is working again. "For a short period of time, there was a bug that redirected people from third party sites with Facebook Login to Facebook.com," a company spokeswoman said in an email. "The issue was quickly resolved."
Asked about how the bug was introduced and whether the company has taken steps to prevent the issue from recurring, Facebook did not respond.
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Hundreds of millions of people log in to third-party websites every month using Facebook Login. The last time anyone from Facebook provided Login usage statistics appears to be in December 2010, when the figure was 250 million people per month. As of March 2012, nine million websites and apps had integrated Facebook Login, according to the company.
But relying on third-party services such as Facebook Login or Google Analytics presents a risk. Ashkan Soltani, an independent security researcher who previously served as staff technologist at the Federal Trade Commission, warns that too few people appreciate the implications of relying on third-party code.
"The browser model allows execution of code from a variety of different sources," explained Soltani in a phone interview. "When you visit a website like CNN's and they embed a third-party service like Facebook Login, you're effectively executing code served by this third party when you visit the website. That has some interesting security implications."