CVE-2025-11720: Mozilla Firefox

High severity, CVSS 8.1. EPSS: 0.3% chance of exploitation in the next 30 days.

The Firefox and Firefox Focus UI for the Android custom tab feature only showed the "site" that was loaded, not the full hostname. User supplied content hosted on a subdomain of a site could have been used to fool a user into thinking it was content from a different subdomain of that site. This vulnerability was fixed in Firefox 144.

Affected products

• Mozilla Firefox: before 144.0 (fixed in 144.0)

Published 2025-10-14. Last modified 2026-10-08.