Mozilla Firefox 3.0.8 and earlier 3.0.x versions allows remote attackers to cause a denial of service (memory corruption) via an XML document composed of a long series of start-tags with no corresponding end-tags. NOTE: it was later reported that 3.0.10 and earlier are also affected.
https://bugzilla.mozilla.org/show_bug.cgi?id=485941
Red Hat does not consider a user-assisted crash of a client application such as Firefox to be a security issue.