Fortunately, latest Firefox blocks most privacy-threatening instances of previously content-accessible resources.
This extension hides private and important metadata of your browser, usually obtainable using
resource://URIs, against the Web. You should have it installed if you use many extensions, because having many extensions means having many tracking and fingerprinting vectors. Also, Web sites can generally probe Firefox for installed extensions in many cases without this. The extension makes that privacy threat less effective. It may break some extensions which depend on this leak.
How to test: Visit https://www.browserleaks.com/firefox before and after installation.
Known issues and support: https://discourse.mozilla-community.org/t/support-no-resource-uri-leak/9004/2?u=desktopd
Looking for a Pale Moon version? This was a lot of work... https://firstname.lastname@example.org
Since many add-ons (and possibly certain part of the browser) depend on this leak available by default, it is expected that some add-ons break due to this fix. (But you are encouraged to report a problem anyway.) This add-on was created as a stop-gap measure. With Mozilla we need to create a browser-level solution that allow both better privacy and functional add-ons. We need more attention to finally fix the root of the problem. Thank you!
If you need to unblock some elements
You can customize the settings in the add-on preferences. about:addons
We want to hear from you
Please do not use the review interface here for reporting problems! It makes it more difficult to collect enough information and share details about the problem. Please use the forum or the issue tracker
Problem reporting guide
Future Tor Browser will include a temporary fix based on this add-on! (Thanks to yawning)