deny-answer-aliases is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the security model used by client browsers. However, a defect in this feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Affects BIND 9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4, 9.12.0->9.12.2, 9.13.0->9.13.2.
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Bind | Isc | 9.7.0 (including) | 9.8.8 (excluding) |
| Bind | Isc | 9.9.0 (including) | 9.9.13 (excluding) |
| Bind | Isc | 9.10.0 (including) | 9.10.8 (excluding) |
| Bind | Isc | 9.11.0 (including) | 9.11.4 (excluding) |
| Bind | Isc | 9.12.0 (including) | 9.12.2 (excluding) |
| Bind | Isc | 9.13.0 (including) | 9.13.2 (excluding) |
| Red Hat Enterprise Linux 6 | RedHat | bind-32:9.8.2-0.68.rc1.el6_10.1 | * |
| Red Hat Enterprise Linux 7 | RedHat | bind-32:9.9.4-61.el7_5.1 | * |
| Bind9 | Ubuntu | bionic | * |
| Bind9 | Ubuntu | devel | * |
| Bind9 | Ubuntu | trusty | * |
| Bind9 | Ubuntu | xenial | * |
While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.