The WebGL implementation in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 on Linux, when a large number of sampler uniforms are used, does not properly interact with Mesa drivers, which allows remote attackers to execute arbitrary code or cause a denial of service (stack memory corruption) via a crafted web site.