Heap-based buffer overflow in the nsSVGFEDiffuseLightingElement::LightPixel function in Mozilla Firefox 4.x through 11.0, Firefox ESR 10.x before 10.0.4, Thunderbird 5.0 through 11.0, Thunderbird ESR 10.x before 10.0.4, and SeaMonkey before 2.9 allows remote attackers to cause a denial of service (invalid gfxImageSurface free operation) or possibly execute arbitrary code by leveraging the use of "different number systems."