The serial_update_parameters function in hw/char/serial.c in QEMU (aka Quick Emulator) allows local guest OS administrators to cause a denial of service (divide-by-zero error and QEMU process crash) via vectors involving a value of divider greater than baud base.
Exploitability
AV:LAC:LPR:HUI:NScope
S:CImpact
C:NI:NA:H6/CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H