When reusing existing popups Firefox would have allowed them to cover the fullscreen notification UI, which could have enabled browser spoofing attacks. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
| Software | From | Fixed in |
|---|---|---|
| mozilla / thunderbird | - | 91.9 |
| mozilla / firefox_esr | - | 91.9 |
| mozilla / firefox | - | 100.0 |