The woff_open_font function in sfnt/sfobjs.c in FreeType before 2.5.4 proceeds with offset+length calculations without restricting length values, which allows remote attackers to cause a denial of service (integer overflow and heap-based buffer overflow) or possibly have unspecified other impact via a crafted Web Open Font Format (WOFF) file.
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.