What’s Vulnerable › Vulnerabilities

CVE-2020-6813

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-03-25 · updated 2026-06-17

Description

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

How to fix

Upgrade to a fixed version: Mozilla Firefox 74.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1605814
• https://www.mozilla.org/security/advisories/mfsa2020-08/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1605814
• https://www.mozilla.org/security/advisories/mfsa2020-08/

Get alerted when CVE-2020-6813 or the next vulnerability affects your stack