This indicates an attack attempt to exploit an Arbitrary File Deletion vulnerability in WordPress.
The vulnerability is due to an input validation error while parsing a crafted HTTP request. A remote attacker could exploit this to delete arbitrary files within the context of the target application, via a crafted HTTP request.
Valid login authentication is required to exploit this vulnerability.
WordPress Core all versions
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the latest patch or update from the vendor.