Is CVE-2022-1520 in the CISA KEV catalog?

No. CVE-2022-1520 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2022-1520?

CVE-2022-1520 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2022-1520?

CVE-2022-1520 has an EPSS score of 0.27% (18th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2022-1520?

Upgrade thunderbird on debian 11 to 1:91.9.0-1~deb11u1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2022-1520

MEDIUM

4.3

CVSS v3

NVD

Description

When viewing an email message A, which contains an attached message B, where B is encrypted or digitally signed or both, Thunderbird may show an incorrect encryption or signature status. After opening and viewing the attached message B, when returning to the display of message A, the message A might be shown with the security status of message B. This vulnerability affects Thunderbird < 91.9.

CWE-346

How to fix

Remediation Available

thunderbirdDebian

Fixed in:1:91.9.0-1~deb11u1CVE-2022-1520

Fixed in:1:91.9.0-1CVE-2022-1520

thunderbirdUbuntu

Fixed in:1:91.9.1+build1-0ubuntu0.18.04.1USN-5435-1

Fixed in:1:91.9.1+build1-0ubuntu0.20.04.1USN-5435-1

Fixed in:1:91.9.1+build1-0ubuntu0.22.04.1USN-5435-1

Mozilla Thunderbird (en-US)Windows application

Affected:91.9Fixed in:91.9Mozilla

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

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.27%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Vendor Advisory2

Related Vulnerabilities

Other CWE-346 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2009-1185	High	7.2	82%	-	Fix
CVE-2025-34291	High	8.8	79%	KEV	-
CVE-2020-16952	High	8.6	71%	-	-
CVE-2023-29711	Critical	9.8	70%	-	-
CVE-2015-4495	High	8.8	70%	KEV	Fix
CVE-2024-23898	High	8.8	67%	-	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 2025-04-16.