Vulnerability Details CVE-2026-84640
A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 4.5%
CVSS Severity
CVSS v3 Score 7.5