Buffer overflow in Sun JDK and Java Runtime Environment (JRE) 5.0 Update 9 and earlier, SDK and JRE 1.4.2_12 and earlier, and SDK and JRE 1.3.1_18 and earlier allows applets to gain privileges via a GIF image with a block with a 0 width field, which triggers memory corruption.
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.