Summer Institute of Linguistics (SIL) Graphite 2, as used in Mozilla Firefox before 15.0, Thunderbird before 15.0, and SeaMonkey before 2.12, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via vectors related to the (1) Silf::readClassMap and (2) Pass::readPass functions.
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.