Critical Security Update for Ruby: Addressing Denial of Service Vulnerability
Summary
ALSA-2026:72484: Important: ruby:4.0 security update. Affects ruby versions < 4.0.6-35.module_el9.8.0+319+116e6235. Fixed in 4.0.6-35.module_el9.8.0+319+116e6235. How to fix ↓
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Background
Ruby is a dynamic, open-source programming language known for its simplicity and productivity. It supports multiple programming paradigms, including functional and object-oriented programming. Ruby is widely used for web development, particularly with the Ruby on Rails framework. However, a recent vulnerability has been identified in the resolv gem, which can lead to uncontrolled memory growth when processing crafted DNS responses, potentially causing a Denial of Service (DoS) attack.
Vulnerability Detail
The vulnerability, identified as CVE-2026-80212, arises from the resolv gem within Ruby. It allows attackers to send specially crafted DNS responses that can lead to excessive memory consumption. This uncontrolled memory growth can result in application crashes or slowdowns, severely impacting the availability of services relying on Ruby applications. The vulnerability is particularly concerning for applications that handle DNS queries, making them susceptible to DoS attacks.
How To Fix
Minimum fixed version
4.0.6-35.module_el9.8.0+319+116e6235
This is the first release that contains the fix.
sudo dnf update rubyTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can limit the memory usage of your Ruby application by configuring resource limits in your operating system. For example, you can use the 'ulimit' command to set memory limits for the Ruby process. However, this is not a permanent solution and updating the package is strongly recommended.
Conclusion
In summary, the vulnerability CVE-2026-80212 in Ruby's resolv gem poses a significant risk of Denial of Service due to uncontrolled memory growth from crafted DNS responses. It is crucial to update to the patched version to mitigate this risk. Additionally, users can utilize Vulert to monitor their applications for vulnerabilities effectively.
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FAQ
CVE-2026-80212 is a vulnerability in the Ruby programming language's resolv gem that can lead to Denial of Service due to uncontrolled memory growth from crafted DNS responses.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which allows you to monitor and alert for open-source vulnerabilities without requiring installation.
The vulnerability can lead to application crashes or slowdowns, affecting the availability of services that rely on Ruby applications, especially those handling DNS queries.
You can update Ruby and its associated packages to the patched version by running the command: sudo dnf update ruby ruby-bundled-gems ruby-default-gems ruby-devel ruby-doc ruby-libs rubygem-bigdecimal rubygem-bundler rubygem-io-console rubygem-irb rubygem-json rubygem-minitest rubygem-mysql2 rubygem-pg rubygem-power_assert rubygem-psych rubygem-racc rubygem-rake rubygem-rbs rubygem-rdoc rubygem-rexml rubygem-rss rubygem-test-unit rubygem-typeprof rubygems rubygems-devel.
A temporary workaround is to limit the memory usage of your Ruby application using the 'ulimit' command, but this is not a permanent solution. Updating the package is recommended.
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