The JavaScript engine in Mozilla Firefox 3.x before 3.0.9, Thunderbird before 2.0.0.22, and SeaMonkey before 1.1.16 allows remote attackers to cause a denial of service (application crash) and possibly trigger memory corruption via vectors involving (1) js_FindPropertyHelper, related to the definitions of Math and Date; and (2) js_CheckRedeclaration.
CWE-399