The content layout component in Mozilla Firefox 3.0 and 3.0.1 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted but well-formed web page that contains "a simple set of legitimate HTML tags."
https://exchange.xforce.ibmcloud.com/vulnerabilities/44169
https://bugzilla.mozilla.org/show_bug.cgi?id=448564
http://www.securityfocus.com/bid/30486
http://www.radware.com/newsevents/pressrelease.aspx?id=6459
http://blog.mozilla.com/security/2008/07/30/low-risk-denial-of-service-in-firefox/