Block 127.0.0.0/8, RFC1918, and others ranges (for Non-Tor SOCKS proxies)
The fix for #10419 (closed) was Tor specific. We rely on Tor blocking localhost, RFC1918, and other non-routable addresses to prevent these requests from going anywhere.
This creates problems for people who want to use Tor Browser with non-Tor SOCKS proxies. The browser will now try to proxy localhost, and it will still continue to proxy RFC1918 addresses, as it did before.
This is not a development priority for us, but we will accept a patch that prevents localhsot, RFC1918, and other internal address space from being proxied in the first place.