CVE-2017-15119

El servidor Network Block Device (NBD) en Quick Emulator (QEMU) en versiones anteriores a la 2.11 es vulnerable a un problema de denegación de servicio (DoS). Esto puede ocurrir si un cliente envía grandes peticiones de opciones, haciendo que el servidor pierda tiempo de CPU al leer hasta 4GB por petición. Un cliente podría usar esta vulnerabilidad para evitar que el servidor NBD sirva otras peticiones, resultando en una denegación de servicio (DoS),

The Network Block Device (NBD) server in Quick Emulator (QEMU), is vulnerable to a denial of service issue. It could occur if a client sent large option requests, making the server waste CPU time on reading up to 4GB per request. A client could use this flaw to keep the NBD server from serving other requests, 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.