NULL Pointer Dereference

QEMU built-in VNC server is vulnerable to NULL Pointer Dereference. The vulnerability is caused due to qemu_clipboard_request() function can be reached before vnc_server_cut_text_caps() function is called and had the chance to initialize the clipboard peer. This can lead to NULL pointer dereference allowing a malicious authenticated VNC client to crash QEMU triggering Denial Of Service (DOS).