The jar protocol handler in Mozilla Firefox before 2.0.0.10 and SeaMonkey before 1.1.7 retrieves the inner URL regardless of its MIME type, and considers HTML documents within a jar archive to have the same origin as the inner URL, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a jar: URI.

Mozilla Firefox before Firefox 2.0.0.13, and SeaMonkey before 1.1.9, can automatically install TLS client certificates with minimal user interaction, and automatically sends these certificates when requested, which makes it easier for remote web sites to track user activities across domains by requesting the TLS client certificates from other domains.