Use-after-free vulnerability in the nsSMILTimeValueSpec::ConvertBetweenTimeContainer function in Mozilla Firefox before 3.6.28 and 4.x through 10.0, Firefox ESR 10.x before 10.0.3, Thunderbird before 3.1.20 and 5.0 through 10.0, Thunderbird ESR 10.x before 10.0.3, and SeaMonkey before 2.8 might allow remote attackers to execute arbitrary code via an SVG animation.