The attack vector is a potential Denial of Service (DoS). The vulnerability is caused by an insufficient check on the length of a decompressed domain name within a DNS packet.
An attacker can craft a malicious DNS packet containing a highly compressed domain name. When the resolv library parses such a packet, the name decompression process consumes a large amount of CPU resources, as the library does not limit the resulting length of the name.
This resource consumption can cause the application thread to become unresponsive, resulting in a Denial of Service condition.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ruby2.5 | Ubuntu | esm-infra/bionic | * |
| Ruby2.7 | Ubuntu | esm-infra/focal | * |
| Ruby3.0 | Ubuntu | jammy | * |
| Ruby3.2 | Ubuntu | noble | * |
| Ruby3.2 | Ubuntu | upstream | * |
| Ruby3.3 | Ubuntu | devel | * |
| Ruby3.3 | Ubuntu | plucky | * |
| Ruby3.3 | Ubuntu | upstream | * |
| Rubygems | Ubuntu | devel | * |
| Rubygems | Ubuntu | plucky | * |
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.