Site Isolation Vulnerability in Firefox Navigation Component
CVE-2026-84129

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox
Vendor: CVE Published:; 1 September 2026

What is CVE-2026-84129?

A site isolation issue exists in the DOM navigation component of Firefox, impacting the browser's ability to securely manage content from different origins. This vulnerability could be exploited to bypass security measures, potentially exposing users to risks. The issue has been addressed in Firefox version 155 and Firefox ESR version 153.2, ensuring enhanced protection for users against possible attacks.