Fullscreen leaks screen size
Summary
When full screen is entered, the real screen size can be extracted. This allows bypassing letterboxing.
Steps to reproduce:
- Go to https://browserleaks.com/javascript
- Press "more" in Screen Resolution section
- "click to test" in Fullscreen Leak Test section
What is the current bug behavior?
Screen resolution is revealed in in fullscreen.
What is the expected behavior?
Screen resolution is not revealed.
This could mean any of the following:
- Letterboxing is applied
- Fullscreen is denied
- Ask to allow fullscreen and then letterbox if accepted
Environment
OS: Qubes OS 4.1 / Whonix 16 Browser: Tor Browser 12.0a2 and 11.5.2