CVE-2026-4371 Affecting MozillaThunderbird package, versions <140.9.0-150200.8.263.1


Severity

Recommended
high

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.36% (28th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-SLES157-MOZILLATHUNDERBIRD-15915540
  • published6 Apr 2026
  • disclosed1 Apr 2026

Introduced: 1 Apr 2026

CVE-2026-4371  (opens in a new tab)

How to fix?

Upgrade SLES:15.7 MozillaThunderbird to version 140.9.0-150200.8.263.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream MozillaThunderbird package and not the MozillaThunderbird package as distributed by SLES. See How to fix? for SLES:15.7 relevant fixed versions and status.

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 Base Scores

version 3.1