The TSymbolTableLevel class in ANGLE, as used in Mozilla Firefox before 47.0 and Firefox ESR 45.x before 45.2 on Windows, allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact by triggering use of a WebGL shader that writes to an array.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.