The remote web server is affected by a remote code execution vulnerability.
The remote web server hosts a version of Jenkins or Jenkins Enterprise that is prior to 1.638 or 1.625.2. It is, therefore, affected by a flaw in the Apache Commons Collections (ACC) library that allows the deserialization of unauthenticated Java objects. An unauthenticated, remote attacker can exploit this to execute arbitrary code on the target host.
Upgrade to Jenkins version 1.638 / 1.625.2 or later. Alternatively, disable the CLI port per the vendor advisory.