Multiple vulnerabilities in the layout engine for Mozilla Firefox 1.5.x before 1.5.0.12 and 2.x before 2.0.0.4, Thunderbird 1.5.x before 1.5.0.12 and 2.x before 2.0.0.4, and SeaMonkey 1.0.9 and 1.1.2 allow remote attackers to cause a denial of service (crash) via vectors related to dangling pointers, heap corruption, signed/unsigned, and other issues.