https://threatpost.com/scheme-flooding-website-tracking/166185/

A flaw that allows browsers to enumerate applications on a machine
threatens cross-browser anonymity in Chrome, Firefox, Microsoft Edge,
Safari and even Tor.

A security researcher has discovered a vulnerability that allows
websites to track users across a number of different desktop browsers
— including Apple Safari, Google Chrome, Microsoft Edge, Mozilla
Firefox and Tor — posing a threat to cross-browser anonymity.

“Cross-browser anonymity is something that even a privacy-conscious
internet user may take for granted,” Darutkin said in his post. “A
website exploiting the scheme-flooding vulnerability could create a
stable and unique identifier that can link those browsing identities
together.”

For instance, someone may use the Tor browser because it’s known for
being “the ultimate in privacy protection;” however, it’s not as fast
or high-performing as other browsers, so someone may opt to use
Safari, Firefox or Chrome for some sites, and Tor when engaging in
anonymous browsing activities — but the bug blows that anonymity out
of the water, Darutkin explained.