FreeType before 2.4.9, as used in Mozilla Firefox Mobile before 10.0.4 and other products, allows remote attackers to cause a denial of service (invalid heap write operation and memory corruption) or possibly execute arbitrary code via a crafted TrueType font.
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.