CVE-2024-26146: Rack Modular Ruby Web Server Interface Vulnerability

Rack, the popular modular Ruby web server interface, has been found to be vulnerable to a denial of service (DoS) attack due to an issue with the header parsing process. This vulnerability is identified as CVE-2024-26146 and affects specific versions of Ruby. This post will provide an in-depth look into the vulnerability, including a code snippet, original references, and exploit details.

Vulnerability Details

CVE-2024-26146 identifies a vulnerability in the Rack web server interface, where specially crafted headers can cause the header parsing process to take longer than expected, potentially leading to a denial of service attack. The headers impacted by this issue include 'Accept' and 'Forwarded.'

Affected Versions

The vulnerability affects Rack applications using Ruby versions prior to 3.2. The following Rack versions are impacted by this vulnerability:

Mitigations

Rack applications running Ruby 3.2 and later have built-in mitigations against this vulnerability. Rack versions 2..9.4, 2.1.4.4, 2.2.8.1, and 3..9.1 have fixed this issue and should be upgraded to as soon as possible.

Code Snippet

The following code snippet demonstrates a simple Rack application that sets and reads the 'Accept' and 'Forwarded' headers of incoming HTTP requests:

require 'rack'

app = Proc.new do |env|
  ['200', {'Content-Type' => 'text/html'}, ['Hello Rack!']]
end

builder = Rack::Builder.new do
  use Rack::CommonLogger
  use Rack::ShowExceptions

  run app
end

Rack::Handler::WEBrick.run(builder, :Port => 9292)

Exploit Details

An attacker could exploit this vulnerability by sending a large number of malicious requests containing specially crafted 'Accept' and 'Forwarded' headers to the target Rack server, causing it to consume excessive resources and potentially crash, effectively causing a denial of service.

Links to Original References

- Rack GitHub Repository: https://github.com/rack/rack
- CVE-2024-26146 Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-26146

Conclusion

CVE-2024-26146 is a denial of service vulnerability that affects specific versions of Rack due to an issue with header parsing. Rack applications using Ruby 3.2 or newer are not impacted by this vulnerability. To protect your Rack application from this vulnerability, upgrade to Rack version 2..9.4, 2.1.4.4, 2.2.8.1, or 3..9.1 immediately. Stay informed about vulnerabilities like these to help keep your web application safe and secure.

Timeline

Published on: 02/29/2024 00:15:51 UTC
Last modified on: 02/29/2024 13:49:47 UTC