WebExtensions with the "ActiveTab" permission are able to access frames hosted within the active tab even if the frames are cross-origin. Malicious extensions can inject frames from arbitrary origins into the loaded page and then interact with them, bypassing same-origin user expectations with this permission. This vulnerability affects Firefox < 58.
| Software | From | Fixed in |
|---|---|---|
| mozilla / firefox | - | 57.0.4.x |
| canonical / ubuntu_linux | 16.04 | 16.04.x |
| canonical / ubuntu_linux | 14.04 | 14.04.x |
| canonical / ubuntu_linux | 17.10 | 17.10.x |