Hi All,

Currently there’s an information leak in Tor Browser: it sends referrer headers containing .onion site addresses when the user clicks on a link on the .onion site.

There’s a fix in the works, but we were wondering:

Does anyone’s hidden service depend on the referrer header?

The currently favoured fix is to stop sending referrers cross-origin (between different .onion sites, and between .onion sites and sites on the internet).

But this may break sites that are set up with multiple .onion addresses and use referrers to check that requests are coming from the parent site. (People sometimes set up different .onion sites to serve different types of content, such as images.)

In general, I would discourage people from using referrers in this way, because they aren’t secure and can be faked.

But does anyone have a compelling use case for cross-origin referrers, or is using them at the moment?

We could include a preference if removing them would break too many sites.

Tim