Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues. This vulnerability affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.

When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. This vulnerability affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.

Уязвимость почтового клиента Thunderbird, связанная с ошибками представления информации пользовательским интерфейсом, позволяющая нарушителю проводить спуфинг атаки

Уязвимость почтового клиента Thunderbird, связанная с переадресацией URL на ненадежный сайт, позволяющая нарушителю перенаправить пользователя на произвольный URL-адрес