CVE-2026-84135: Mozilla Firefox Mobile

Critical severity, CVSS 9.8. EPSS: 0.4% chance of exploitation in the next 30 days.

Other issue in Firefox Focus for Android. This vulnerability was fixed in Firefox 155.

Affected products

• Mozilla Firefox Mobile: before 155.0 (fixed in 155.0)

Published 2026-09-01. Last modified 2026-09-03.