When a user typed a URL in the address bar or the search bar and quickly hit the enter key, a website could sometimes capture that event and then redirect the user before navigation occurred to the desired, entered address. To construct a convincing spoof the attacker would have had to guess what the user was typing, perhaps by suggesting it. This vulnerability affects Firefox < 84.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-26979
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1641287%2C1673299
• https://www.mozilla.org/security/advisories/mfsa2020-54/