Tomcat 4.0 through 4.1.12, using mod_jk 1.2.1 module on Apache 1.3 through 1.3.27, allows remote attackers to cause a denial of service (desynchronized communications) via an HTTP GET request with a Transfer-Encoding chunked field with invalid values.
https://exchange.xforce.ibmcloud.com/vulnerabilities/10771
http://archives.neohapsis.com/archives/bugtraq/2002-12/0045.html