CVE-2024-47220 is a security vulnerability identified in the WEBrick HTTP server toolkit for Ruby, specifically versions through 1.8.1. WEBrick is a Ruby library used to build HTTP servers, often for development or lightweight applications. The vulnerability enables HTTP request smuggling, a technique where an attacker sends a single HTTP request with both Content-Length and Transfer-Encoding headers, causing the server and intermediaries to interpret the request boundaries differently. This can result in the server processing multiple requests from a single crafted request, potentially allowing attackers to bypass security controls, poison web caches, or gain unauthorized access to sensitive endpoints. The example given is embedding a "GET /admin HTTP/1.1" request inside a "POST /user HTTP/1.1" request. The root cause is WEBrick's improper handling of conflicting headers, which violates HTTP protocol expectations. The supplier's position is that WEBrick should not be used in production, highlighting that this toolkit is primarily intended for development or testing. No official patches or CVSS scores have been published yet, and there are no known exploits in the wild. However, the vulnerability poses a significant risk where WEBrick is used in production or exposed to untrusted networks. HTTP request smuggling attacks can be leveraged to bypass authentication, conduct web cache poisoning, or perform cross-user attacks, impacting confidentiality, integrity, and availability of web applications relying on WEBrick.

The impact of CVE-2024-47220 can be significant for organizations using WEBrick in production environments. HTTP request smuggling can allow attackers to bypass security controls such as firewalls, intrusion detection systems, and authentication mechanisms by manipulating how requests are parsed. This can lead to unauthorized access to restricted resources, session hijacking, web cache poisoning, and data leakage. Additionally, attackers might disrupt service availability by injecting malicious requests or causing server confusion. Although WEBrick is generally recommended only for development, some legacy or small-scale applications may still use it in production, exposing them to these risks. The vulnerability affects the confidentiality, integrity, and availability of web services relying on WEBrick, potentially compromising sensitive data and application functionality. Since exploitation does not require authentication or user interaction, the attack surface is broad wherever WEBrick is exposed to untrusted clients. The absence of known exploits currently limits immediate widespread impact, but the vulnerability should be addressed proactively to prevent future attacks.

To mitigate CVE-2024-47220, organizations should first avoid using WEBrick in production environments as recommended by the supplier. For applications currently using WEBrick, migrating to more secure and actively maintained HTTP server frameworks such as Puma, Unicorn, or Passenger is strongly advised. If migration is not immediately feasible, organizations should implement network-level protections including web application firewalls (WAFs) configured to detect and block HTTP request smuggling attempts, specifically requests containing both Content-Length and Transfer-Encoding headers. Additionally, strict input validation and header sanitization should be enforced on incoming HTTP requests. Monitoring HTTP traffic for anomalous patterns indicative of request smuggling can help detect exploitation attempts. Developers should stay alert for official patches or updates from the Ruby or WEBrick maintainers and apply them promptly once available. Finally, restricting access to WEBrick servers to trusted internal networks and disabling exposure to the public internet can reduce risk.