knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Knot_resolver | Nic | * | 4.3.0 (excluding) |
| Knot-resolver | Ubuntu | bionic | * |
| Knot-resolver | Ubuntu | disco | * |
| Knot-resolver | Ubuntu | eoan | * |
| Knot-resolver | Ubuntu | esm-apps/bionic | * |
| Knot-resolver | Ubuntu | esm-apps/xenial | * |
| Knot-resolver | Ubuntu | focal | * |
| Knot-resolver | Ubuntu | groovy | * |
| Knot-resolver | Ubuntu | hirsute | * |
| Knot-resolver | Ubuntu | impish | * |
| Knot-resolver | Ubuntu | trusty | * |
| Knot-resolver | Ubuntu | upstream | * |
| Knot-resolver | Ubuntu | xenial | * |