Mozilla Firefox Mobile — CVE-2026-84135 (Critical)

Date Sep 1, 2026

Type Vendor advisory

Signal Critical vendor advisory

Vendor / Product Mozilla · Firefox Mobile

CVE CVE-2026-84135

Critical vendor advisory CVE-2026-84135

Summary

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

Why it matters

This CVE carries a CRITICAL severity rating (CVSS 9.8) in Mozilla Firefox Mobile. Patch or mitigate promptly. EPSS percentile: 3%.

Operator check

Review CVE-2026-84135 in your asset inventory. Apply patches per vendor guidance and verify Firefox Mobile is not exposed. CVSS score: 9.8. EPSS probability: 0.1%; percentile: 3%.

Sources

NVD — CVE-2026-84135 Source reference Source reference

PatchBrief uses public sources. It does not scan environments, verify exposure, or replace vendor guidance.

Get watched-vendor alerts Subscribe free Back to feed