java/org/apache/coyote/ajp/AbstractAjpProcessor.java in Apache Tomcat 8.x before 8.0.4 allows remote attackers to cause a denial of service (thread consumption) by using a "Content-Length: 0" AJP request to trigger a hang in request processing.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.