This indicates an attack attempt to exploit a Memory Corruption vulnerability in QEMU VNC.
The vulnerability is caused by lack of proper validation when the vulnerable software handle a maliciously crafted packet. A remote attacker can exploit this to execute arbitrary code within context of the affected software.
QEMU QEMU prior to commit e6908bfe8e07f2b4
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.