VULNERABILITY INTELLIGENCE

CVE-2026-4371

CVSS score7.4 HIGH
EPSS probability0.37%
CISA KEVNot currently listed
Published2026-03-24
Last modified2026-07-15
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

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.

Weakness classification

  • 134c704f-9b21-4f2e-91b3-4a467353bcc0: CWE-126
  • 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-130

Primary references