Apache Tomcat before 6.0.39, 7.x before 7.0.47, and 8.x before 8.0.0-RC3, when an HTTP connector or AJP connector is used, does not properly handle certain inconsistent HTTP request headers, which allows remote attackers to trigger incorrect identification of a request's length and conduct request-smuggling attacks via (1) multiple Content-Length headers or (2) a Content-Length header and a "Transfer-Encoding: chunked" header. NOTE: this vulnerability exists because of an incomplete fix for CVE-2005-2090.

Jakarta Tomcat 5.0.19 (Coyote/1.1) and Tomcat 4.1.24 (Coyote/1.0) allows remote attackers to poison the web cache, bypass web application firewall protection, and conduct XSS attacks via an HTTP request with both a "Transfer-Encoding: chunked" header and a Content-Length header, which causes Tomcat to incorrectly handle and forward the body of the request in a way that causes the receiving server to process it as a separate HTTP request, aka "HTTP Request Smuggling."