CVE-2017-7816: Mozilla Firefox

Medium severity, CVSS 5.3. EPSS: 1.3% chance of exploitation in the next 30 days.

WebExtensions could use popups and panels in the extension UI to load an "about:" privileged URL, violating security checks that disallow this behavior. 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.