Heap-based buffer overflow in Apple Quicktime before 7.0.4 allows remote attackers to execute arbitrary code via a GIF image file with a crafted Netscape Navigator Application Extension Block that modifies the heap in the Picture Modifier block.
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.