Heap-based buffer overflow in Cirrus CLGD 54xx VGA Emulator in Quick Emulator (Qemu) 2.8 and earlier allows local guest OS users to execute arbitrary code or cause a denial of service (crash) via vectors related to a VNC client updating its display after a VGA operation.
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.