ruby/webrick

ruby webrick through v1.9.2 WEBrick reparses trailer Content-Length into canonical request state, enabling request smuggling. NOTE: the Supplier reports that "The project README states that it is suitable for testing and development, and that its developers do not encourage its use to serve production web applications that may be subject to hostile input. It is not a production web server and is not intended to receive traffic from untrusted sources. Request smuggling is only reachable when WEBrick sits behind a proxy and receives hostile traffic in a production deployment, which is the configuration the project documents as discouraged."

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

An issue was discovered in the WEBrick toolkit through 1.8.1 for Ruby. It allows HTTP request smuggling by providing both a Content-Length header and a Transfer-Encoding header, e.g., "GET /admin HTTP/1.1\r\n" inside of a "POST /user HTTP/1.1\r\n" request. NOTE: the supplier's position is "Webrick should not be used in production."

An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not checked the transfer-encoding header value rigorously. An attacker may potentially exploit this issue to bypass a reverse proxy (which also has a poor header check), which may lead to an HTTP Request Smuggling attack.

The WEBrick gem 1.4.2 for Ruby allows directory traversal if the attacker once had local access to create a symlink to a location outside of the web root directory. NOTE: The vendor states that this is analogous to Options FollowSymlinks in the Apache HTTP Server, and therefore it is "not a problem.