CVE-2017-7817: Mozilla Firefox

Medium severity, CVSS 5.3. EPSS: 1.2% chance of exploitation in the next 30 days.

A spoofing vulnerability can occur when a page switches to fullscreen mode without user notification, allowing a fake address bar to be displayed. This allows an attacker to spoof which page is actually loaded and in use. Note: This attack only affects Firefox for Android. Other operating systems are not affected. This vulnerability affects Firefox < 56.

Affected products

• Mozilla Firefox: up to and including 55.0.3

Published 2018-06-11. Last modified 2026-06-17.