The texImage2D implementation in the WebGL subsystem in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 does not properly interact with Mesa drivers, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via function calls involving certain values of the level parameter.