Improper Handling of Length Parameter Inconsistency Affecting thunderbird package, versions <0:140.9.0-1.el9_6


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.36% (28th percentile)

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  • Snyk IDSNYK-RHEL9-THUNDERBIRD-16083003
  • published16 Apr 2026
  • disclosed24 Mar 2026

Introduced: 24 Mar 2026

CVE-2026-4371  (opens in a new tab)
CWE-130  (opens in a new tab)

How to fix?

Upgrade RHEL:9 thunderbird to version 0:140.9.0-1.el9_6 or higher.
This issue was patched in RHSA-2026:8284.

NVD Description

Note: Versions mentioned in the description apply only to the upstream thunderbird package and not the thunderbird package as distributed by RHEL. See How to fix? for RHEL:9 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