CVE-2026-4371 Details
Description
A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
A vulnerability exists in Mozilla Thunderbird versions prior to 149 and versions prior to 140.9. This issue allows a malicious mail server to send improperly formatted strings with negative lengths, which can cause the email parser to read memory outside of its allocated buffer. Such exploitation could lead to a parser malfunction, potentially crashing Thunderbird or causing a leak of sensitive information.
Users can upgrade to Thunderbird versions 149 or 140.9 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 25, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-126 | Buffer Over-read | CISA-ADP |
| CWE-130 | Improper Handling of Length Parameter Inconsistency | redhat-SADP |
Affected Products
| Product | Versions |
|---|---|
| mozilla thunderbird | < 140.9.0 < 149.0 |
CPE
Remediation
| |
Change History
8 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | CVE Modified | redhat-SADP |
| Jun 30, 2026 | CVE Modified | redhat-SADP |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 13, 2026 | CVE Modified | [email protected] |
| Mar 27, 2026 | Initial Analysis | [email protected] |
| Mar 25, 2026 | CVE Modified | CISA-ADP |
| Mar 24, 2026 | New CVE Received | [email protected] |