The resolver in nginx before 1.8.1 and 1.9.x before 1.9.10 does not properly limit CNAME resolution, which allows remote attackers to cause a denial of service (worker process resource consumption) via vectors related to arbitrary name resolution.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Nginx | F5 | 0.6.18 (including) | 1.8.1 (excluding) |
| Nginx | F5 | 1.9.0 (including) | 1.9.10 (excluding) |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | rh-nginx18-nginx-1:1.8.1-1.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6.6 EUS | RedHat | rh-nginx18-nginx-1:1.8.1-1.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUS | RedHat | rh-nginx18-nginx-1:1.8.1-1.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | rh-nginx18-nginx-1:1.8.1-1.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUS | RedHat | rh-nginx18-nginx-1:1.8.1-1.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUS | RedHat | rh-nginx18-nginx-1:1.8.1-1.el7 | * |
| Nginx | Ubuntu | devel | * |
| Nginx | Ubuntu | esm-infra-legacy/trusty | * |
| Nginx | Ubuntu | esm-infra/xenial | * |
| Nginx | Ubuntu | precise | * |
| Nginx | Ubuntu | trusty | * |
| Nginx | Ubuntu | trusty/esm | * |
| Nginx | Ubuntu | upstream | * |
| Nginx | Ubuntu | vivid | * |
| Nginx | Ubuntu | wily | * |
| Nginx | Ubuntu | xenial | * |
| Nginx | Ubuntu | yakkety | * |
| Nginx | 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.