When browsing a document hosted on an IP address, an attacker could insert certain characters to flip domain and path information in the address bar. This vulnerability affects Firefox < 77.
https://www.mozilla.org/security/advisories/mfsa2020-20/
https://bugzilla.mozilla.org/show_bug.cgi?id=1623888