CVE-2024-26142: Exploring a Possible ReDoS Vulnerability in Rails 7.1. – 7.1.3 Accept Header Parsing

The world of web applications has become significantly sophisticated and complex in recent years, with more and more features and capabilities being incorporated into frameworks like Ruby on Rails. As these technologies continue to improve, it is essential to stay abreast of the potential vulnerabilities and security implications that can emerge in the course of development.

In this post, we will investigate a possible ReDoS (Regular Expression Denial of Service) vulnerability found in the Accept header parsing routines of Ruby on Rails' Action Dispatch module (Rails version 7.1. to 7.1.3). We'll also look at how Rails developers can mitigate this vulnerability, especially those using Ruby 3.2 or newer.

Vulnerability Details

Beginning in Rails version 7.1., there is a potential ReDoS vulnerability in the Accept header parsing of Action Dispatch. This issue was reported under the CVE identifier CVE-2024-26142 and was later patched in 7.1.3.1.

In a nutshell, ReDoS vulnerabilities can lead to a server becoming vulnerable to denial-of-service attacks, as it may end up spending considerable resources in processing regular expression patterns within incoming requests. This particular vulnerability in Rails arises from the way it handles the Accept header in HTTP requests, which can result in performance issues if exploited. The vulnerability has the potential to render Rails applications unresponsive or even crash the server entirely.

Link to original references

1. Rails GitHub Issue
2. Rails Security Announcement
3. CVE Details
4. NVD - CVE-2024-26142

Code Snippet

Here is a code snippet that comprises the problematic part of the Rails Accept header handling in version 7.1.2 (vulnerable version). Notice the use of regular expressions in the parsing process:

module ActionController
  module MimeResponds
    class InvalidAcceptHeader < StandardError
    end

    # Vulnerable code
    def accepts
      @accepts ||= Mime::Type.parse(request.accept)
    rescue Mime::Type::InvalidMimeType
      raise InvalidAcceptHeader, "Invalid Accept header: #{request.accept}"
    end
    # End vulnerable code
  end
end

Mitigation

Fortunately, Ruby 3.2 includes built-in mitigations for this vulnerability. As such, Rails applications that are implemented using Ruby 3.2 or newer are not affected by CVE-2024-26142.

For Rails applications built on Ruby versions earlier than 3.2, it is recommended to upgrade to Rails 7.1.3.1 or a later patch version, which resolves the vulnerability in the Accept header handling. Additionally, developers should ensure their Ruby installations are up to date to minimize the risk of ReDoS attacks in their applications.

Conclusion

CVE-2024-26142 serves as yet another reminder of the importance of staying informed about potential security risks in web application development. Through proper vigilance and adhering to the latest updates and patches, Rails developers can continue to build confidence in their web applications' ability to withstand vulnerabilities like ReDoS attacks. When working with Rails and Ruby, it is essential to remain responsive to emerging security threats and adjust your development practices accordingly.

Timeline

Published on: 02/27/2024 16:15:46 UTC
Last modified on: 02/28/2024 14:07:00 UTC