Firefox and Mozilla can associate a cookie with multiple domains when the DNS resolver has a non-root domain in its search list, which allows remote attackers to trick a user into accepting a cookie for a hostname formed via search-list expansion of the hostname entered by the user, or steal a cookie for an expanded hostname, as demonstrated by an attacker who operates an ap1.com Internet web site to steal cookies associated with an ap1.com.example.com intranet web site.

Mozilla before 1.7.6, and Firefox before 1.0.1, allows remote attackers to spoof arbitrary web sites by injecting content from one window into a target window whose name is known but resides in a different domain, as demonstrated using a pop-up window on a trusted web site, aka the "window injection" vulnerability.

Mozilla Firefox before the Preview Release, Mozilla before 1.7.3, and Thunderbird before 0.8 may allow remote attackers to trick users into performing unexpected actions, including installing software, via signed scripts that request enhanced abilities using the enablePrivilege parameter, then modify the meaning of certain security-relevant dialog messages.

The XPInstall installer in Mozilla Firefox before the Preview Release, Mozilla before 1.7.3, and Thunderbird before 0.8 sets insecure permissions for certain installed files within xpi packages, which could allow local users to overwrite arbitrary files or execute arbitrary code.

Mozilla Firefox before the Preview Release, Mozilla before 1.7.3, and Thunderbird before 0.8 allows untrusted Javascript code to read and write to the clipboard, and possibly obtain sensitive information, via script-generated events such as Ctrl-Ins.

The Linux install .tar.gz archives for Mozilla Firefox before the Preview Release, Mozilla before 1.7.3, and Thunderbird before 0.8, create certain files with insecure permissions, which could allow local users to overwrite those files and execute arbitrary code.

Mozilla before 1.4.2 executes Javascript events in the context of a new page while it is being loaded, allowing it to interact with the previous page (zombie document) and enable cross-domain and cross-site scripting (XSS) attacks, as demonstrated using onmousemove events.

The POP3 mail client in Mozilla 1.0 and earlier, and Netscape Communicator 4.7 and earlier, allows remote attackers to cause a denial of service (no new mail) via a mail message containing a dot (.) at a newline, which is interpreted as the end of the message.

Mozilla 0.9.6 and earlier and Netscape 6.2 and earlier allows remote attackers to steal cookies from another domain via a link with a hex-encoded null character (%00) followed by the target domain.