I would be more concerned about the 8 year old Jenkins 1.656 version than about that particular vulnerability. There are probably other critical vulnerabilities in the version you use. Just go over the list of advisories Security Advisories.
The script to disable the CLI is definitely written in mind for current Jenkins versions not older than maybe 1 or 2 years.
Thanks for your response, yes we are planning to upgrade.
We have never done this before, can you please suggest what documents we should follow to upgrade the existing version to latest one?