The WYSIWYG rendering engine ("rich mail" editor) in Mozilla Thunderbird 1.0.7 and earlier allows user-assisted attackers to bypass javascript security settings and obtain sensitive information or cause a crash via an e-mail containing a javascript URI in the SRC attribute of an IFRAME tag, which is executed when the user edits the e-mail.

Mozilla Firefox before 1.5.0.1, Thunderbird 1.5 if running Javascript in mail, and SeaMonkey before 1.0 allow remote attackers to execute arbitrary code by changing an element's style from position:relative to position:static, which causes Gecko to operate on freed memory.

GUI display truncation vulnerability in Mozilla Thunderbird 1.0.2, 1.0.6, and 1.0.7 allows user-assisted attackers to execute arbitrary code via an attachment with a filename containing a large number of spaces ending with a dangerous extension that is not displayed by Thunderbird, along with an inconsistent Content-Type header, which could be used to trick a user into downloading dangerous content by dragging or saving the attachment.

Mozilla Thunderbird 1.0 and Firefox 1.0.6 allows remote attackers to obfuscate URIs via a long URI, which causes the address bar to go blank and could facilitate phishing attacks.