Critical Vulnerability in Ruby Rack Package: Log Injection via Newline Characters
Summary
UBUNTU-CVE-2025-25184: Rack provides an interface for developing web applications in Ruby. Affects ruby-rack versions < 1.5.2-3+deb8u3ubuntu1~esm9. Fixed in 1.5.2-3+deb8u3ubuntu1~esm9. How to fix ↓
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Background
Ruby Rack is a modular Ruby web server interface that provides a simple and efficient way to develop web applications. It acts as a middleware layer, allowing developers to build applications that can communicate with web servers. The package is widely used in Ruby on Rails applications and other Ruby-based frameworks. However, it has been found to be vulnerable to a log injection issue that can be exploited under specific conditions, potentially leading to log manipulation and data integrity issues.
Vulnerability Detail
The vulnerability arises from the Rack::CommonLogger component, which can be exploited by crafting input that includes newline characters. This allows an attacker to manipulate log entries by injecting malicious content into the logs. When a user provides authorization credentials via Rack::Auth::Basic, the username is stored in env['REMOTE_USER'] and logged by Rack::CommonLogger. If the username contains CRLF (Carriage Return Line Feed) characters, the logger will record these characters, leading to broken log formats or fraudulent entries. This can obscure legitimate activity and allow for the injection of malicious data into log files.
How To Fix
Minimum fixed version
1.5.2-3+deb8u3ubuntu1~esm9
This is the first release that contains the fix.
sudo apt-get install --only-upgrade ruby-rackTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using usernames that contain CRLF characters and ensure that input validation is implemented to sanitize user inputs before they are logged. This can help mitigate the risk of log injection until the package is updated.
Conclusion
The Ruby Rack package has a critical vulnerability that allows for log injection through newline characters in usernames. This can lead to serious consequences, including log manipulation and data integrity issues. It is crucial to update the package to the latest patched version to mitigate these risks. Temporary workarounds should be implemented until an update can be performed.
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FAQ
The vulnerability allows for log injection through the use of newline characters in usernames, which can manipulate log entries.
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If exploited, this vulnerability can lead to log manipulation, obscuring real activity, and potentially injecting malicious data into log files.
Yes, patched versions of the Ruby Rack package are available for various Ubuntu distributions. It is recommended to update to these versions.
Implement input validation to sanitize usernames and avoid using CRLF characters as a temporary measure until the package can be updated.
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