The navigator.plugins implementation in Mozilla Firefox before 3.5.12 and 3.6.x before 3.6.9, Thunderbird before 3.0.7 and 3.1.x before 3.1.3, and SeaMonkey before 2.0.7 does not properly handle destruction of the DOM plugin array, which might allow remote attackers to cause a denial of service (application crash) or execute arbitrary code via crafted access to the navigator object, related to a "dangling pointer vulnerability."