An out-of-bounds read/write access flaw was found in the USB emulator of the QEMU. This issue occurs while processing USB packets from a guest when USBDevice ‘setup_len’ exceeds its ‘data_buf[4096]’ in the do_token_in, do_token_out routines. This flaw allows a guest user to crash the QEMU process, resulting in a denial of service, or the potential execution of arbitrary code with the privileges of the QEMU process on the host.
Using Libvirt management interface to manage guest VMs significantly reduces impact of this issue. Libvirt starts each guest process with an unprivileged system user(ex. qemu) privileges and further confines the process with strict sVirt and SELinux policies.