CVE-2026-4371 Affecting thunderbird package, versions <0:140.9.0-1.el10_1.alma.1


Severity

Recommended
high

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.06% (19th percentile)

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  • Snyk IDSNYK-ALMALINUX10-THUNDERBIRD-15909788
  • published5 Apr 2026
  • disclosed1 Apr 2026

Introduced: 1 Apr 2026

CVE-2026-4371  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:10 thunderbird to version 0:140.9.0-1.el10_1.alma.1 or higher.
This issue was patched in ALSA-2026:6342.

NVD Description

Note: Versions mentioned in the description apply only to the upstream thunderbird package and not the thunderbird package as distributed by AlmaLinux. See How to fix? for AlmaLinux:10 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