When in an endless loop, a website specifying a custom cursor using CSS could make it look like the user is interacting with the user interface, when they are not. This could lead to a perceived broken state, especially when interactions with existing browser dialogs and warnings do not work. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.
| Software | From | Fixed in |
|---|---|---|
| mozilla / thunderbird | - | 78.1 |
| mozilla / firefox_esr | - | 78.1 |
| mozilla / firefox | - | 79.0 |
| canonical / ubuntu_linux | 18.04 | 18.04.x |
| canonical / ubuntu_linux | 20.04 | 20.04.x |
| canonical / ubuntu_linux | 16.04 | 16.04.x |