CVE-2018-5683

La función vga_draw_text en Qemu permite que usuarios del sistema operativo invitados con privilegios provoquen una denegación de servicio (acceso de lectura fuera de límites y cierre inesperado del proceso Qemu) aprovechando la validación indebida de direcciones de memoria.

An out-of-bounds read access issue was found in the VGA emulator of QEMU. It could occur in vga_draw_text routine, while updating display area for a vnc client. A privileged user inside a guest could use this flaw to crash the QEMU process resulting in DoS.

USN-3575-1 fixed vulnerabilities in QEMU. The fix for CVE-2017-11334 caused a regression in Xen environments. This update removes the problematic fix pending further investigation. It was discovered that QEMU incorrectly handled guest ram. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. David Buchanan discovered that QEMU incorrectly handled the VGA device. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 17.10. Thomas Garnier discovered that QEMU incorrectly handled multiboot. An attacker could use this issue to cause QEMU to crash, resulting in a denial of service, or possibly execute arbitrary code on the host. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. Various other issues were also addressed.