Is CVE-2021-38495 in the CISA KEV catalog?

No. CVE-2021-38495 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-38495?

CVE-2021-38495 has a CVSS v3 base score of 8.8 (HIGH).

What is the EPSS score for CVE-2021-38495?

CVE-2021-38495 has an EPSS score of 1.07% (61th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-38495?

Upgrade thunderbird on ubuntu 18.04 to 1:91.5.0+build1-0ubuntu0.18.04.1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-38495

HIGH

8.8

CVSS v3

NVD

Description

Mozilla developers reported memory safety bugs present in Thunderbird 78.13.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Thunderbird < 91.1 and Firefox ESR < 91.1.

CWE-787Out-of-bounds Write

How to fix

Remediation Available

thunderbirdUbuntu

Fixed in:1:91.5.0+build1-0ubuntu0.18.04.1USN-5248-1

Fixed in:1:91.5.0+build1-0ubuntu0.20.04.1USN-5248-1

Mozilla Firefox ESR (en-US)Windows application

Affected:91.1Fixed in:91.1Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:91.1Fixed in:91.1Mozilla

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

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

1.07%probability of exploitation in 30 days

61stpercentile

Moderate risk: more likely to be exploited than 61% of all known CVEs.

References

Vendor Advisory3

Third-Party Advisory2

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2023-4863	High	8.8	100%	KEV	Fix
CVE-2020-16040	Medium	6.5	100%	-	Fix

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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.