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.