HTTP Request Smuggling Vulnerability in Ruby WEBrick
Summary
CVE-2025-6442: Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. Affects ruby-webrick versions < ee60354bcb84ec33b9245e1d1aa6e1f7e8132101. No fix is published. 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 is designed to provide a lightweight server for serving web applications and is often used in development environments. Despite its simplicity, WEBrick is capable of handling HTTP requests and responses, making it a useful tool for developers. However, it is vulnerable to an HTTP request smuggling issue that can be exploited under certain conditions, particularly when deployed behind an HTTP proxy.
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, allowing remote attackers to smuggle arbitrary HTTP requests. The implications of this vulnerability are significant, as it can enable attackers to bypass security measures, manipulate server behavior, and potentially gain unauthorized access to sensitive data or systems.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, consider deploying Ruby WEBrick behind a more secure HTTP proxy that can mitigate the effects of this vulnerability. Additionally, ensure that your server is configured to validate and sanitize incoming HTTP requests to prevent potential exploitation.
Conclusion
The Ruby WEBrick HTTP request smuggling vulnerability (CVE-2025-6442) poses significant risks to applications using this toolkit. It is crucial to update to the patched versions of the package and implement security measures to protect against potential exploitation.
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FAQ
CVE-2025-6442 is a vulnerability in Ruby WEBrick that allows remote attackers to perform HTTP request smuggling due to inconsistent parsing of HTTP header terminators.
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 access to the code.
The risks include unauthorized access to sensitive data, manipulation of server behavior, and potential bypassing of security measures, leading to further exploitation.
Yes, a patch is available. For Debian 12 and 13, ensure you update to the latest version or at least version 1.9.1-1 for Debian 13.
If immediate updates are not possible, consider implementing a secure HTTP proxy and validating incoming requests to mitigate the risk of exploitation.
Related vulnerabilities
Recent vulnerabilities recorded for ruby-webrick.
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