The JavaScript engine in Mozilla Firefox and Thunderbird 1.x before 1.5 and 1.0.x before 1.0.8, Mozilla Suite before 1.7.13, and SeaMonkey before 1.0 does not properly handle temporary variables that are not garbage collected, which might allow remote attackers to trigger operations on freed memory and cause memory corruption.

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.

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.

Firefox before 1.0.5, Thunderbird before 1.0.5, Mozilla before 1.7.9, Netscape 8.0.2, and K-Meleon 0.9 runs XBL scripts even when Javascript has been disabled, which makes it easier for remote attackers to bypass such protection.