CSRF Vulnerability on "Send Message" functionality

There is a CSRF Vulnerability on "Send Message" functionality.
Using this we can send any message,select its visibility and also select whether to send to everyone or any particular user.

POC URL: http://localhost:8080/xwiki-enterprise-web-5.1/bin/view/Main/MessageSenderMacro?xpage=plain&xaction=postMessage&messagestream_message=testaaabbbb&visibilityLevel=everyone&targetName=

Using the parameter "messagestream_message" we can customize the message to send.

Using the parameter "visibilityLevel" we can customize the visibility.

Using the parameter "targetName" we can customize whether to send to a particular user or to all followers.

Vulnerability tested on XWIKI 5.1, so lower versions are also affected.