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.

Firefox before 1.0 and Mozilla before 1.7.5 display the SSL lock icon when an insecure page loads a binary file from a trusted site, which could facilitate phishing attacks.

Mozilla allows remote attackers to cause a denial of service (application crash from null dereference or infinite loop) via a web page that contains a (1) TEXTAREA, (2) INPUT, (3) FRAMESET or (4) IMG tag followed by a null character and some trailing characters, as demonstrated by mangleme.

Mozilla allows remote attackers to cause a denial of service (application crash from invalid memory access) via an "unusual combination of visual elements," including several large MARQUEE tags with large height parameters, as demonstrated by mangleme.