This indicates an attack attempt to perform an Arbitrary File Upload vulnerability in different WebApp Plugins by XAttacker Tool.
XAttacker is a tool that targets different Web Applications plugins. A remote attacker can use it to upload an arbitrary file onto vulnerable systems via a crafted request.
Insecure Web Application Plugins
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.