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 may lead to an HTTP Request Smuggling attack. A flaw was found in the way the Ruby REXML library parsed XML documents. Parsing a specially crafted XML document using REXML and writing parsed data back to a new XML document results in creating a document with a different structure. This issue could affect the integrity of processed data in applications using REXML that parse XML documents, write data back to XML, and re-parse them again