Critical Security Update for ruby4.0: Denial of Service Vulnerability

ruby4.0 Updated 29 Sep 2026

Summary

28/09/2026

Disclosed on

N/A

Severity

Yes i

Fix available

Unrated

Severity

Not published

CVSS Score

ALSA-2026:72427: Important: ruby4.0 security update. Affects ruby4.0 versions < 4.0.6-37.el10_2. Fixed in 4.0.6-37.el10_2. How to fix ↓

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Background

Ruby is a dynamic, open-source programming language with a focus on simplicity and productivity. It is widely used for web development and scripting tasks. The ruby4.0 package, specifically designed for AlmaLinux 10, provides essential tools and libraries for Ruby programming. However, it has been identified to have a vulnerability that can lead to denial of service due to uncontrolled memory growth when processing crafted DNS responses.

Vulnerability Detail

The vulnerability, identified as CVE-2026-80212, arises from the resolv gem within ruby4.0. Attackers can exploit this flaw by sending specially crafted DNS responses, which can cause the application to consume excessive memory, leading to a denial of service. This can severely impact the availability of applications relying on Ruby for DNS resolution, making it critical for users to address this issue promptly.

How To Fix

Minimum fixed version

4.0.6-37.el10_2

This is the first release that contains the fix.

sudo dnf update ruby4.0

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Workaround

As a temporary workaround, users can limit the DNS responses processed by the application or implement rate limiting on DNS queries to mitigate the impact of this vulnerability until the update can be applied.

Conclusion

The ruby4.0 package has a critical vulnerability that can lead to denial of service through crafted DNS responses. It is essential for users to update to the latest patched version to ensure the security and availability of their applications. Temporary workarounds can be implemented until the update is applied.

See every vulnerability recorded for ruby4.0 →