CVE-2020-6813: Mozilla Firefox

Medium severity, CVSS 5.3. EPSS: 1.2% chance of exploitation in the next 30 days.

When protecting CSS blocks with the nonce feature of Content Security Policy, the @import statement in the CSS block could allow an attacker to inject arbitrary styles, bypassing the intent of the Content Security Policy. This vulnerability affects Firefox < 74.

Affected products

• Mozilla Firefox: before 74.0 (fixed in 74.0)

Published 2020-03-25. Last modified 2026-06-17.