CVE-2021-43529

thunderbird: Memory corruption when processing S/MIME messages

Severity Score

9.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Attend

*SSVC

Descriptions

Thunderbird versions prior to 91.3.0 are vulnerable to the heap overflow described in CVE-2021-43527 when processing S/MIME messages. Thunderbird versions 91.3.0 and later will not call the vulnerable code when processing S/MIME messages that contain certificates with DER-encoded DSA or RSA-PSS signatures.

A flaw was found in Thunderbird, which is vulnerable to the heap overflow described in CVE-2021-43527 when processing S/MIME messages. Thunderbird versions 91.3.0 and later will not call the vulnerable code when processing S/MIME messages that contain certificates with DER-encoded DSA or RSA-PSS signatures.

Multiple security issues were discovered in Thunderbird, which could result in the execution of arbitrary code, spoofing, information disclosure, downgrade attacks on SMTP STARTTLS connections or misleading display of OpenPGP/MIME signatures.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Complete

Integrity

Complete

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:Attend

Exploitation

None

Automatable

Yes

Tech. Impact

Total

* Organization's Worst-case Scenario

Timeline

2021-11-08 CVE Reserved
2022-01-28 CVE Published
2025-03-19 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-787: Out-of-bounds Write

CAPEC

References (5)

URL	Tag	Source
https://bugzilla.mozilla.org/show_bug.cgi?id=CVE-2021-43529	Issue Tracking

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2021-43529	2021-11-04
https://bugzilla.redhat.com/show_bug.cgi?id=2088353	2021-11-04
https://access.redhat.com/security/cve/CVE-2021-43527	2021-11-04
https://access.redhat.com/security/vulnerabilities/RHSB-2021-008	2021-11-04

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Mozilla Search vendor "Mozilla"		Thunderbird Search vendor "Mozilla" for product "Thunderbird"				< 91.3.0 Search vendor "Mozilla" for product "Thunderbird" and version " < 91.3.0"		-		Affected