CVE-2026-4371

HIGH EPSS 20.2%
Published Mar 24, 20263mo ago · Modified Jun 17, 20262w ago
7.4 CVSS 3.1
High
Find Similar
Published Mar 24, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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 Details

Base Score
7.4
Exploitability
2.2
Impact
5.2
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
20.2% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-126

Affected Products 2

VendorProductVersionRange
mozillathunderbird* <140.9.0
mozillathunderbird* <149.0

References 3

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=2023493
    Permissions Required
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-23/
    Vendor Advisory
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-24/
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.