Is CVE-2020-12421 in the CISA KEV catalog?

No. CVE-2020-12421 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2020-12421?

CVE-2020-12421 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2020-12421?

CVE-2020-12421 has an EPSS score of 1.84% (76th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2020-12421?

Upgrade firefox on debian unstable to 78.0-1 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2020-12421

MEDIUMEPSS 76th pctl

6.5

CVSS v3

NVD

Description

When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.

CWE-295Improper Certificate Validation

How to fix

Remediation Available

firefoxDebian

Fixed in:78.0-1CVE-2020-12421

firefoxUbuntu

Fixed in:78.0.1+build1-0ubuntu0.16.04.1USN-4408-1

Fixed in:78.0.1+build1-0ubuntu0.18.04.1USN-4408-1

Fixed in:78.0.1+build1-0ubuntu0.20.04.1USN-4408-1

thunderbirdUbuntu

Fixed in:1:68.10.0+build1-0ubuntu0.16.04.1USN-4421-1

Fixed in:1:68.10.0+build1-0ubuntu0.18.04.1USN-4421-1

Fixed in:1:68.10.0+build1-0ubuntu0.20.04.1USN-4421-1

DeveloperEditionWindows application

Affected:78.0Fixed in:78.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:78.0Fixed in:78.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:68.10.0Fixed in:68.10.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:68.10.0Fixed in:68.10.0Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

1.84%probability of exploitation in 30 days

76thpercentile

Elevated risk: more likely to be exploited than 76% of all known CVEs.

References

Vendor Advisory4

Third-Party Advisory3

Other references4

Related Vulnerabilities

Other CWE-295 (Improper Certificate Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2015-4000	Low	3.7	100%	-	Fix
CVE-2020-0601	High	8.1	89%	KEV	Fix
CVE-2009-3555	Critical	9.8	87%	-	Fix
CVE-2022-26923	High	8.8	83%	KEV	Fix
CVE-2023-27823	Critical	9.8	53%	-	-
CVE-2022-42979	High	8.8	24%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.