CVE-2026-84641 Information disclosure due to malicious IMAP server response

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...

CVE-2026-84639 Uninitialized memory in MIME parsing

Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2...

Security Vulnerabilities fixed in Thunderbird 155 — Mozilla

Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. A maliciously constructed mail header could lead to a one byte read past the end of a buffer. A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID...