CVE-2020-6810: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 1% chance of exploitation in the next 30 days.

After a website had entered fullscreen mode, it could have used a previously opened popup to obscure the notification that indicates the browser is in fullscreen mode. Combined with spoofing the browser chrome, this could have led to confusing the user about the current origin of the page and credential theft or other attacks. This vulnerability affects Firefox < 74.

Affected products

• Mozilla Firefox: before 74.0 (fixed in 74.0)

Published 2020-03-25. Last modified 2026-06-17.