Is CVE-2020-6821 in the CISA KEV catalog?

No. CVE-2020-6821 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2020-6821?

CVE-2020-6821 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2020-6821?

CVE-2020-6821 has an EPSS score of 1.47% (71th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2020-6821?

Upgrade firefox on debian unstable to 75.0-1 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2020-6821

HIGHEPSS 71th pctl

7.5

CVSS v3

NVD

Description

When reading from areas partially or fully outside the source resource with WebGL's copyTexSubImage method, the specification requires the returned values be zero. Previously, this memory was uninitialized, leading to potentially sensitive data disclosure. This vulnerability affects Thunderbird < 68.7.0, Firefox ESR < 68.7, and Firefox < 75.

CWE-908

How to fix

Remediation Available

firefoxDebian

Fixed in:75.0-1CVE-2020-6821

firefoxUbuntu

Fixed in:75.0+build3-0ubuntu0.16.04.1USN-4323-1

Fixed in:75.0+build3-0ubuntu0.18.04.1USN-4323-1

thunderbirdUbuntu

Fixed in:1:68.7.0+build1-0ubuntu0.16.04.2USN-4335-1

Fixed in:1:68.7.0+build1-0ubuntu0.18.04.1USN-4328-1

DeveloperEditionWindows application

Affected:75.0Fixed in:75.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:75.0Fixed in:75.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:68.7.0Fixed in:68.7.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:68.7.0Fixed in:68.7.0Mozilla

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 InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

1.47%probability of exploitation in 30 days

71stpercentile

Elevated risk: more likely to be exploited than 71% of all known CVEs.

References

Vendor Advisory3

Third-Party Advisory1

usn.ubuntu.com

Issue Tracking1

bugzilla.mozilla.org

Related Vulnerabilities

Other CWE-908 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2023-24941	Critical	9.8	95%	-	Fix
CVE-2007-1751	High	9.3	61%	-	-
CVE-2008-0081	Critical	9.8	58%	-	-
CVE-2020-1934	Medium	5.3	52%	-	Fix
CVE-2011-1255	High	9.3	42%	-	-

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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.