CVE-2012-4210: Mozilla Firefox

High severity, CVSS 9.3. EPSS: 3.5% chance of exploitation in the next 30 days.

The Style Inspector in Mozilla Firefox before 17.0 and Firefox ESR 10.x before 10.0.11 does not properly restrict the context of HTML markup and Cascading Style Sheets (CSS) token sequences, which allows user-assisted remote attackers to execute arbitrary JavaScript code with chrome privileges via a crafted stylesheet.

Affected products

• Mozilla Firefox: up to and including 16.0.2; version 0.1 only; version 0.2 only; version 0.3 only; version 0.4 only; version 0.5 only; …

Published 2012-11-21. Last modified 2026-06-16.