You may find it troubling that when you follow a link in Tab 1 (Site A) which is targeted to open Site B in a new window or tab, Site B can change the page in Tab 1 from Site A to Site B, or Site C, or whatever it wants.

This script adds two rel attribute values (rel="noopener noreferrer") to such targeted links to limit the potential for that. It does not attempt to clean up uses of window.open(), however.

An unfortunate (?) side effect: Site B cannot tell the source of the referral was Site A. This may break "hotlink protection" or other aspects of authentication on some sites.

To disable this global script on a specific site: Use the Greasemonkey / Tampermonkey user excludes feature to prevent the script from running on the source site (the site with the links you want to work normally).

References:

• https://www.reddit.com/r/firefox/comments/50nz1m/is_it_possible_to_protected_yourself_from/
• https://mathiasbynens.github.io/rel-noopener/