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CVE-2020-6813

16
FAUCET Score

CVE-2020-6813 describes a vulnerability in Firefox versions prior to 74 where the Content Security Policy's nonce feature for CSS blocks could be bypassed. An attacker could inject arbitrary styles via the @import statement within a CSS block, circumventing the intended security controls. This medium-severity vulnerability (CVSS 5.3) requires no user interaction and has a low impact on integrity, with no confidentiality or availability impact. There is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 74.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 74CPE match
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.17%
Probability of exploitation in next 30 days
EPSS Percentile
64.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0117 is in the 42nd percentile among its peer group of 23,725 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (3)

mozillavendor investigatingvia nvd_reference
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox

Vendor Advisories (1)

redhatCVE-2020-6813Low

Mozilla: @import statements in CSS could bypass the Content Security Policy nonce feature

Mar 10, 2020

References

bugzilla.mozilla.org / show_bug.cgi
Permissions RequiredVendor Advisory
mozilla.org / security/advisories/mfsa2020-08
Vendor Advisory