Hello,
Current Latest version is 12.1.6 MP6 (12.1 RU6 MP6) which is released this month.
Here are the 2 article, you may like to check -
Download the latest version of Symantec Endpoint Protection
https://support.symantec.com/en_US/article.TECH103088.html
Released versions of Symantec Endpoint Protection
https://support.symantec.com/en_US/article.TECH154475.html
Regards,