CVE-2025-24294 resolv vulnerable to DoS via insufficient DNS domain name length validation
An attacker can cause a Denial of Service in applications using the Ruby resolv library by sending malicious DNS packets that trigger excessive CPU consumption during name decompression.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-24294?
CVE-2025-24294 is a high-severity denial of service vulnerability in Ruby resolv, published on 12 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-400
Which versions are affected by CVE-2025-24294?
6 open source packages ship an affected version, including resolv.
| Package | Affected | Fixed in |
|---|---|---|
resolv RubyGems | All versions | 0.2.3 |
resolv RubyGems | All versions | 0.2.3 |
resolv RubyGems | From 0.3.0 | 0.3.1 |
resolv RubyGems | From 0.3.0 | 0.3.1 |
resolv RubyGems | From 0.4.0 | 0.6.2 |
resolv RubyGems | From 0.4.0 | 0.6.2 |
Linux distribution packages (2)
ruby2.5 SUSE:Linux Enterprise Module for Basesystem 15 SP6 | All versions | 2.5.9-150000.4.54.1 |
ruby2.5 openSUSE:Leap 15.6 | All versions | 2.5.9-150000.4.54.1 |
How do I fix CVE-2025-24294?
Upgrade resolv to a fixed version for your release line: 0.2.3, 0.3.1 or 0.6.2.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-24294 being exploited?
There is no known exploitation of CVE-2025-24294 in the wild and no public exploit code.
Sources
Also known as AZL-65202, AZL-65241, BELL-CVE-2025-24294, CLSA-2026-1768209702, CLSA-2026-1768301582, DEBIAN-CVE-2025-24294 and 10 more.