This indicates an attack attempt to exploit a Cross-Site Scripting Vulnerability in XWiki.org XWiki.
The vulnerability is due to insufficient validation of deleted attachment file names. A remote, authenticated attacker could exploit this vulnerability by sending a crafted request to the target server. Successful exploitation could result in the execution of script code in the security context of a target user's browser.
XWiki.org XWiki 13.x prior to 13.10.6
XWiki.org XWiki 14.x prior to 14.3
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.