Site Isolation Flaw in Firefox's CSS Parsing Component
CVE-2026-74986

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox
Vendor: CVE Published:; 18 August 2026

What is CVE-2026-74986?

A site isolation vulnerability exists within the CSS Parsing and Computation component of Firefox that could potentially allow malicious sites to execute unwanted actions on behalf of a user. This vulnerability was addressed in the most recent updates, specifically Firefox version 154 and Firefox ESR version 153.1. Users are encouraged to stay updated for enhanced security.