The js_dtoa function in Mozilla Firefox 2.x before 2.0.0.1, 1.5.x before 1.5.0.9, Thunderbird before 1.5.0.9, and SeaMonkey before 1.0.7 overwrites memory instead of exiting when the floating point precision is reduced, which allows remote attackers to cause a denial of service via any plugins that reduce the precision.