Buffer overflow in unpack200 in Java SE Development Kit (JDK) and Java Runtime Environment (JRE) 5.0 Update 17 and earlier, and 6 Update 12 and earlier, allows remote attackers to access files or execute arbitrary code via a JAR file with crafted Pack200 headers.
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.