An exploitable memory corruption vulnerability exists in the JBIG2 parser of Artifex MuPDF 1.9. A specially crafted PDF can cause a negative number to be passed to a memset resulting in memory corruption and potential code execution. An attacker can specially craft a PDF and send to the victim to trigger this vulnerability.
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.