You would like to know whether Symantec Endpoint Protection (SEP) 12.1 or 14 is vulnerable to Apache Struts (CVE-2017-5638).
SEP 12.1 and 14 are not vulnerable to the Apache Struts CVE-2017-5638 vulnerability.
SEP 12.1 and 14 both have the capability to detect an attempted exploit of this vulnerability via Intrusion Prevention. The attack signature for this is Attack: Apache Struts CVE-2017-5638.