Security Advisory
CVE-2026-84641
7.5
HIGH
Vulnerability Description
A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Published Date
September 1, 2026
Official Source
NIST NVD Advisory