The Artofdefence Hyperguard Web Application Firewall (WAF) module before 2.5.5-11635 3.0 before 3.0.3-11636 and 3.1 before 3.1.1-11637 a module for the Apache HTTP Server allows remote attackers to cause a denial of service (memory consumption) via an HTTP request with a large Content-Length value but no POST data.