CVE-2025-24294: Possible Denial of Service in resolv gem

Posted by mame on 8 Jul 2025

A denial of service vulnerability has been discovered in the resolv gem bundled with Ruby. This vulnerability has been assigned the CVE identifier CVE-2025-24294. We recommend upgrading the resolv gem.

Details

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.

Affected versions

The vulnerability affects the resolv gem bundled with the following Ruby series:

• Ruby 3.2 series: resolv version 0.2.2 and earlier
• Ruby 3.3 series: resolv version 0.3.0
• Ruby 3.4 series: resolv version 0.6.1 and earlier

Credits

Thanks to Manu for discovering this issue.

History

• Originally published at 2025-07-08 07:00:00 (UTC)