The get_tile function in Mozilla Firefox before 33.0, Firefox ESR 31.x before 31.2, and Thunderbird 31.x before 31.2 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly execute arbitrary code via WebM frames with invalid tile sizes that are improperly handled in buffering operations during video playback.
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.