Critical Security Flaw in Ruby Packages: Denial of Service and Command Injection Vulnerabilities
Summary
ALSA-2026:33565: Important: ruby security update. Affects ruby versions < 3.3.10-13.el10_2. Fixed in 3.3.10-13.el10_2. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
Ruby is an extensible, interpreted, object-oriented scripting language widely used for web development and system management tasks. It provides features for processing text files and managing system resources efficiently. However, recent vulnerabilities have been identified in its net-imap library, which can lead to severe security risks, including denial of service and command injection attacks.
Vulnerability Detail
The vulnerabilities stem from flaws in the Net::IMAP component of Ruby, which can be exploited through crafted IMAP responses, leading to a denial of service (CVE-2026-42245). Additionally, an IMAP command injection vulnerability exists due to improper handling of symbol arguments (CVE-2026-42258). Furthermore, a man-in-the-middle attack can bypass TLS, resulting in information disclosure (CVE-2026-42246). These vulnerabilities can compromise the integrity and availability of applications relying on Ruby's net-imap library.
How To Fix
Minimum fixed version
3.3.10-13.el10_2
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
If immediate patching is not feasible, consider implementing network-level controls to restrict access to the IMAP service, thereby mitigating the risk of exploitation until the packages can be updated.
Conclusion
The identified vulnerabilities in Ruby's net-imap library pose significant security risks that can affect the integrity and availability of applications. It is crucial to apply the necessary updates to mitigate these risks and ensure the security of your Ruby applications.
See every vulnerability recorded for ruby →
FAQ
The vulnerabilities include denial of service, command injection, and information disclosure via man-in-the-middle attacks.
You can use Vulert's playground at Vulert Scanner to check if your application is impacted by these vulnerabilities without needing to sign up.
Exploiting these vulnerabilities can lead to application downtime, unauthorized command execution, and sensitive data exposure.
Yes, Vulert provides real-time monitoring and alerts for open-source vulnerabilities using just a manifest file like package-lock.json.
Implement network-level controls to limit access to the IMAP service as a temporary workaround until you can apply the updates.
Related vulnerabilities
Recent vulnerabilities recorded for ruby.
