Firefox vulnerability

What happened

The fullscreen notification is prematurely hidden when fullscreen is re-requested quickly by the user. This could have been leveraged to perform a potential spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.

Affected versions

Firefox: before 135.0; 131.0 through before 135.0 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.