CVE-2026-4371

Advisory lineage Upstream: 0 Downstream: 18
Modified
Published: 24 Mar 2026, 20:27
Last modified:15 Jul 2026, 00:55

Vulnerability Summary

Overall Risk (default)
medium
30/100
CVSS Score
7.4 HIGH
v3.1 (cve.org)
EPSS Score
0.36% LOW
0% probability +0.07%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

24 Mar 2026, 20:27
Published
Vulnerability first disclosed
15 Jul 2026, 00:55
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS Trends

Current EPSS score: 0.36%• Percentile: 28%

Techniques & Countermeasures

  • CWE-126•Buffer Over-read

    The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer.

  • CWE-130•Improper Handling of Length Parameter Inconsistency

    The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.

Affected Systems

  • mozilla•thunderbird

    ≥ unspecified, < 149 | ≥ unspecified, < 140.9 | < 140.9.0 | < 149.0

References (18)