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.
| Software | From | Fixed in |
|---|---|---|
| mozilla / firefox | - | 83.0 |
| mozilla / firefox_esr | - | 78.5 |
| mozilla / thunderbird | - | 78.5 |