Mozilla Firefox - Critical Security Warning for all versions
Users should avoid links in unsolicited email messages and untrusted URLs regardless of which browser they use. Based on past experience, the Mozilla foundation has a priority on security, so I'm certain this will be addressed soon with a new release of Firefox.
Firefox/Deerpark all versions - Critical Security Warning
Tom Ferris has discovered a vulnerability in Firefox, which can be exploited by malicious people to cause a DoS (Denial of Service) or potentially to compromise a user's system. The vulnerability is caused due to an error in the handling of an URL that contains the 0xAD character in its domain name. This can be exploited to cause a heap-based buffer overflow.
Successful exploitation crashes Firefox and may potentially allow code execution but requires that the user is tricked into visiting a malicious web site or open a specially crafted HTML file. The vulnerability has been confirmed in version 1.0.6, and is reported to affect versions prior to 1.0.6, and version 1.5 Beta 1.