The vast majority of websites you visit are sending your data to third-party sources, usually without your permission or knowledge. That’s not exactly breaking news, but the sheer scale and ubiquity of that leakage might be.

Tim Libert, a privacy researcher with the University of Pennsylvania, has published new peer-reviewed research that sought to quantify all the “privacy compromising mechanisms” on the one million most popular websites worldwide. His conclusion? “Findings indicate that nearly 9 in 10 websites leak user data to parties of which the user is likely unaware.”

Libert used his own open source software called webXray—the same program he’s used in the past to analyze trackers installed on health and porn websites—and he found that not only were most siphoning user data, they were sharing it all over the place.

“Sites that leak user data contact an average of nine external domains,” he wrote in the new paper, published in the International Journal of Communication, “indicating that users may be tracked by multiple entities in tandem.” Read more…