HTTP Request Smuggling Vulnerability in Ruby WEBrick Package
Summary
UBUNTU-CVE-2025-6442: Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. Affects ruby-webrick versions < 1.7.0-3ubuntu0.2. Fixed in 1.7.0-3ubuntu0.2. How to fix ↓
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Background
Ruby WEBrick is a simple HTTP server toolkit that is part of the Ruby standard library. It provides a way to create web servers and handle HTTP requests and responses. WEBrick is often used for development and testing purposes due to its simplicity and ease of use. However, it has been found to be vulnerable to an HTTP request smuggling attack, which can allow remote attackers to exploit the server under specific conditions.
Vulnerability Detail
The vulnerability, identified as CVE-2025-6442, arises from a flaw in the read_headers method of Ruby WEBrick. This flaw leads to inconsistent parsing of HTTP header terminators, enabling attackers to smuggle arbitrary HTTP requests when the server is deployed behind an HTTP proxy that meets certain conditions. The ramifications of this vulnerability can be severe, as it allows attackers to manipulate requests and potentially gain unauthorized access to sensitive information or perform actions on behalf of legitimate users.
How To Fix
Minimum fixed version
1.7.0-3ubuntu0.2
This is the first release that contains the fix.
sudo apt-get install --only-upgrade ruby-webrickTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate patching is not possible, consider implementing a web application firewall (WAF) to filter and monitor HTTP requests for malicious patterns. Additionally, ensure that your server is not directly exposed to the internet and is behind a secure proxy.
Conclusion
The Ruby WEBrick package is vulnerable to an HTTP request smuggling attack, which can have serious security implications. It is crucial to update to the patched versions of the package to mitigate this risk. Additionally, utilizing tools like Vulert can help monitor for vulnerabilities in your applications.
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FAQ
CVE-2025-6442 is a vulnerability in the Ruby WEBrick package that allows remote attackers to perform HTTP request smuggling.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which analyzes your manifest file for vulnerabilities.
The vulnerability can lead to unauthorized access, data leakage, and manipulation of requests, posing significant security risks.
Yes, patches are available for various versions of the Ruby WEBrick package. Ensure you update to the latest version as specified in the 'how_to_fix' section.
Vulert is a service that monitors and alerts for open-source vulnerabilities in software using a manifest file. It provides real-time insights without requiring code access.
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