Bahruz Jabiyev, Steven Sprecher and Kaan Onarlioglu of NEU seclab reports:
Apache Tomcat did not correctly parse the HTTP transfer-encoding request header in some circumstances leading to the possibility to request smuggling when used with a reverse proxy. Specifically: Tomcat incorrectly ignored the transfer-encoding header if the client declared it would only accept an HTTP/1.0 response; Tomcat honoured the identify encoding; and Tomcat did not ensure that, if present, the chunked encoding was the final encoding.