It was possible to cause the browser to enter fullscreen mode without displaying the security UI; thus making it possible to attempt a phishing attack or otherwise confuse the user. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5. Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26953 Reference (s):
- https://www.mozilla.org/security/advisories/mfsa2020-50/
- URL: https://www.mozilla.org/security/advisories/mfsa2020-50/
- https://www.mozilla.org/security/advisories/mfsa2020-51/
- URL: https://www.mozilla.org/security/advisories/mfsa2020-51/
- https://www.mozilla.org/security/advisories/mfsa2020-52/