CVE-2026-92238

Analyzed Analyzed - Analysis Complete

Memory Corruption in Thunderbird via Malformed Mail Headers

Publication date: 2026-09-15

Last updated on: 2026-09-24

Assigner: Mozilla Corporation

Description

A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156 and Thunderbird 140.16.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-15

Last Modified

2026-09-24

Generated

2026-10-06

AI Q&A

2026-09-16

EPSS Evaluated

2026-10-04

NVD

CVE-2026-92238

EUVD

EUVD-2026-79242

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	thunderbird	to 140.16.0 (exc)
mozilla	thunderbird	From 141.0 (inc) to 153.3.0 (exc)
mozilla	thunderbird	From 154.0 (inc) to 156.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-444	The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

Attack-Flow Graph

Executive Summary

This vulnerability involves a maliciously crafted mail header that could cause multiple fields to be parsed as a single field or trigger memory safety violations. It was addressed in Thunderbird versions 156 and 140.16.

Impact Analysis

An attacker could exploit this to manipulate email headers, potentially leading to misinterpretation of data or crashes due to memory safety issues. This may result in email processing errors or system instability.

Compliance Impact

The provided CVE data does not specify how this vulnerability affects compliance with standards like GDPR or HIPAA. The vulnerability involves maliciously crafted mail headers leading to parsing issues or memory safety violations, but no direct impact on regulatory compliance is mentioned.

Mitigation Strategies

Update Thunderbird to version 156 or 140.16 or later to address the vulnerability. Remove or disable any affected versions of Thunderbird until patched.

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