The Network Block Device (NBD) server in Quick Emulator (QEMU) before 2.11 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.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Qemu | Qemu | * | 2.11.0 (excluding) |
| Red Hat OpenStack Platform 10.0 (Newton) | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Red Hat OpenStack Platform 11.0 (Ocata) | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Red Hat OpenStack Platform 12.0 (Pike) | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Red Hat OpenStack Platform 8.0 (Liberty) | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Red Hat OpenStack Platform 9.0 (Mitaka) | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Red Hat Virtualization 4 for Red Hat Enterprise Linux 7 | RedHat | qemu-kvm-rhev-10:2.10.0-21.el7 | * |
| Qemu | Ubuntu | artful | * |
| Qemu | Ubuntu | esm-infra/xenial | * |
| Qemu | Ubuntu | upstream | * |
| Qemu | Ubuntu | xenial | * |
| Qemu | Ubuntu | zesty | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.